diff --git a/django/contrib/postgres/fields/citext.py b/django/contrib/postgres/fields/citext.py
index 2dac2577d1..01df5411ab 100644
--- a/django/contrib/postgres/fields/citext.py
+++ b/django/contrib/postgres/fields/citext.py
@@ -1,78 +1,45 @@
-import warnings
-
 from django.db.models import CharField, EmailField, TextField
-from django.test.utils import ignore_warnings
-from django.utils.deprecation import RemovedInDjango51Warning
 
-__all__ = ["CICharField", "CIEmailField", "CIText", "CITextField"]
+__all__ = ["CICharField", "CIEmailField", "CITextField"]
 
 
-# RemovedInDjango51Warning.
-class CIText:
-    def __init__(self, *args, **kwargs):
-        warnings.warn(
-            "django.contrib.postgres.fields.CIText mixin is deprecated.",
-            RemovedInDjango51Warning,
-            stacklevel=2,
-        )
-        super().__init__(*args, **kwargs)
-
-    def get_internal_type(self):
-        return "CI" + super().get_internal_type()
-
-    def db_type(self, connection):
-        return "citext"
-
-
-class CICharField(CIText, CharField):
-    system_check_deprecated_details = {
+class CICharField(CharField):
+    system_check_removed_details = {
         "msg": (
-            "django.contrib.postgres.fields.CICharField is deprecated. Support for it "
-            "(except in historical migrations) will be removed in Django 5.1."
+            "django.contrib.postgres.fields.CICharField is removed except for support "
+            "in historical migrations."
         ),
         "hint": (
             'Use CharField(db_collation="…") with a case-insensitive non-deterministic '
             "collation instead."
         ),
-        "id": "fields.W905",
+        "id": "fields.E905",
     }
 
-    def __init__(self, *args, **kwargs):
-        with ignore_warnings(category=RemovedInDjango51Warning):
-            super().__init__(*args, **kwargs)
 
-
-class CIEmailField(CIText, EmailField):
-    system_check_deprecated_details = {
+class CIEmailField(EmailField):
+    system_check_removed_details = {
         "msg": (
-            "django.contrib.postgres.fields.CIEmailField is deprecated. Support for it "
-            "(except in historical migrations) will be removed in Django 5.1."
+            "django.contrib.postgres.fields.CIEmailField is removed except for support "
+            "in historical migrations."
         ),
         "hint": (
             'Use EmailField(db_collation="…") with a case-insensitive '
             "non-deterministic collation instead."
         ),
-        "id": "fields.W906",
+        "id": "fields.E906",
     }
 
-    def __init__(self, *args, **kwargs):
-        with ignore_warnings(category=RemovedInDjango51Warning):
-            super().__init__(*args, **kwargs)
 
-
-class CITextField(CIText, TextField):
-    system_check_deprecated_details = {
+class CITextField(TextField):
+    system_check_removed_details = {
         "msg": (
-            "django.contrib.postgres.fields.CITextField is deprecated. Support for it "
-            "(except in historical migrations) will be removed in Django 5.1."
+            "django.contrib.postgres.fields.CITextField is removed except for support "
+            "in historical migrations."
         ),
         "hint": (
             'Use TextField(db_collation="…") with a case-insensitive non-deterministic '
             "collation instead."
         ),
-        "id": "fields.W907",
+        "id": "fields.E907",
     }
-
-    def __init__(self, *args, **kwargs):
-        with ignore_warnings(category=RemovedInDjango51Warning):
-            super().__init__(*args, **kwargs)
diff --git a/django/db/backends/postgresql/operations.py b/django/db/backends/postgresql/operations.py
index aa839f5634..93eb982f4b 100644
--- a/django/db/backends/postgresql/operations.py
+++ b/django/db/backends/postgresql/operations.py
@@ -159,9 +159,6 @@ class DatabaseOperations(BaseDatabaseOperations):
             "CharField",
             "EmailField",
             "TextField",
-            "CICharField",
-            "CIEmailField",
-            "CITextField",
         ):
             return "%s::text"
 
@@ -179,9 +176,6 @@ class DatabaseOperations(BaseDatabaseOperations):
         ):
             if internal_type in ("IPAddressField", "GenericIPAddressField"):
                 lookup = "HOST(%s)"
-            # RemovedInDjango51Warning.
-            elif internal_type in ("CICharField", "CIEmailField", "CITextField"):
-                lookup = "%s::citext"
             else:
                 lookup = "%s::text"
 
diff --git a/docs/ref/checks.txt b/docs/ref/checks.txt
index e641c989e3..9170ff83a8 100644
--- a/docs/ref/checks.txt
+++ b/docs/ref/checks.txt
@@ -237,13 +237,19 @@ Model fields
   except for support in historical migrations.
 * **fields.W905**: ``django.contrib.postgres.fields.CICharField`` is
   deprecated. Support for it (except in historical migrations) will be removed
-  in Django 5.1.
+  in Django 5.1. *This check appeared in Django 4.2 and 5.0*.
+* **fields.E905**: ``django.contrib.postgres.fields.CICharField`` is removed
+  except for support in historical migrations.
 * **fields.W906**: ``django.contrib.postgres.fields.CIEmailField`` is
   deprecated. Support for it (except in historical migrations) will be removed
-  in Django 5.1.
+  in Django 5.1. *This check appeared in Django 4.2 and 5.0*.
+* **fields.E906**: ``django.contrib.postgres.fields.CIEmailField`` is removed
+  except for support in historical migrations.
 * **fields.W907**: ``django.contrib.postgres.fields.CITextField`` is
   deprecated. Support for it (except in historical migrations) will be removed
-  in Django 5.1.
+  in Django 5.1. *This check appeared in Django 4.2 and 5.0*.
+* **fields.E907**: ``django.contrib.postgres.fields.CITextField`` is removed
+  except for support for historical migrations.
 
 File fields
 ~~~~~~~~~~~
diff --git a/docs/ref/contrib/postgres/fields.txt b/docs/ref/contrib/postgres/fields.txt
index 0348bb235f..ec767b50e9 100644
--- a/docs/ref/contrib/postgres/fields.txt
+++ b/docs/ref/contrib/postgres/fields.txt
@@ -277,71 +277,6 @@ transform do not change. For example:
     at the database level and cannot be supported in a logical, consistent
     fashion by Django.
 
-``CIText`` fields
-=================
-
-.. class:: CIText(**options)
-
-    .. deprecated:: 4.2
-
-    A mixin to create case-insensitive text fields backed by the citext_ type.
-    Read about `the performance considerations`_ prior to using it.
-
-    To use ``citext``, use the :class:`.CITextExtension` operation to
-    :ref:`set up the citext extension <create-postgresql-extensions>` in
-    PostgreSQL before the first ``CreateModel`` migration operation.
-
-    If you're using an :class:`~django.contrib.postgres.fields.ArrayField`
-    of ``CIText`` fields, you must add ``'django.contrib.postgres'`` in your
-    :setting:`INSTALLED_APPS`, otherwise field values will appear as strings
-    like ``'{thoughts,django}'``.
-
-    Several fields that use the mixin are provided:
-
-.. class:: CICharField(**options)
-
-    .. deprecated:: 4.2
-
-        ``CICharField`` is deprecated in favor of
-        ``CharField(db_collation="…")`` with a case-insensitive
-        non-deterministic collation.
-
-.. class:: CIEmailField(**options)
-
-    .. deprecated:: 4.2
-
-        ``CIEmailField`` is deprecated in favor of
-        ``EmailField(db_collation="…")`` with a case-insensitive
-        non-deterministic collation.
-
-.. class:: CITextField(**options)
-
-    .. deprecated:: 4.2
-
-        ``CITextField`` is deprecated in favor of
-        ``TextField(db_collation="…")`` with a case-insensitive
-        non-deterministic collation.
-
-    These fields subclass :class:`~django.db.models.CharField`,
-    :class:`~django.db.models.EmailField`, and
-    :class:`~django.db.models.TextField`, respectively.
-
-    ``max_length`` won't be enforced in the database since ``citext`` behaves
-    similar to PostgreSQL's ``text`` type.
-
-    .. _citext: https://www.postgresql.org/docs/current/citext.html
-    .. _the performance considerations: https://www.postgresql.org/docs/current/citext.html#id-1.11.7.19.9
-
-.. admonition:: Case-insensitive collations
-
-    It's preferable to use non-deterministic collations instead of the
-    ``citext`` extension. You can create them using the
-    :class:`~django.contrib.postgres.operations.CreateCollation` migration
-    operation. For more details, see :ref:`manage-postgresql-collations` and
-    the PostgreSQL documentation about `non-deterministic collations`_.
-
-    .. _non-deterministic collations: https://www.postgresql.org/docs/current/collation.html#COLLATION-NONDETERMINISTIC
-
 ``HStoreField``
 ===============
 
diff --git a/docs/releases/5.1.txt b/docs/releases/5.1.txt
index 9a0cd94f7e..d4510d30db 100644
--- a/docs/releases/5.1.txt
+++ b/docs/releases/5.1.txt
@@ -260,3 +260,10 @@ to remove usage of these features.
 * The ``django.contrib.auth.hashers.SHA1PasswordHasher``,
   ``django.contrib.auth.hashers.UnsaltedSHA1PasswordHasher``, and
   ``django.contrib.auth.hashers.UnsaltedMD5PasswordHasher`` are removed.
+
+* The model ``django.contrib.postgres.fields.CICharField``,
+  ``django.contrib.postgres.fields.CIEmailField``, and
+  ``django.contrib.postgres.fields.CITextField`` are removed, except for
+  support in historical migrations.
+
+* The ``django.contrib.postgres.fields.CIText`` mixin is removed.
diff --git a/tests/backends/postgresql/tests.py b/tests/backends/postgresql/tests.py
index 947d51ea1e..590dbe6073 100644
--- a/tests/backends/postgresql/tests.py
+++ b/tests/backends/postgresql/tests.py
@@ -368,13 +368,6 @@ class Tests(TestCase):
         for lookup in lookups:
             with self.subTest(lookup=lookup):
                 self.assertIn("::text", do.lookup_cast(lookup))
-        # RemovedInDjango51Warning.
-        for lookup in lookups:
-            for field_type in ("CICharField", "CIEmailField", "CITextField"):
-                with self.subTest(lookup=lookup, field_type=field_type):
-                    self.assertIn(
-                        "::citext", do.lookup_cast(lookup, internal_type=field_type)
-                    )
 
     def test_correct_extraction_psycopg_version(self):
         from django.db.backends.postgresql.base import Database, psycopg_version
diff --git a/tests/invalid_models_tests/test_deprecated_fields.py b/tests/invalid_models_tests/test_deprecated_fields.py
index 429e15febc..65f65e7528 100644
--- a/tests/invalid_models_tests/test_deprecated_fields.py
+++ b/tests/invalid_models_tests/test_deprecated_fields.py
@@ -104,46 +104,42 @@ class DeprecatedFieldsTests(SimpleTestCase):
         self.assertEqual(
             PostgresCIFieldsModel.check(),
             [
-                checks.Warning(
-                    "django.contrib.postgres.fields.CICharField is deprecated. Support "
-                    "for it (except in historical migrations) will be removed in "
-                    "Django 5.1.",
+                checks.Error(
+                    "django.contrib.postgres.fields.CICharField is removed except for "
+                    "support in historical migrations.",
                     hint=(
                         'Use CharField(db_collation="…") with a case-insensitive '
                         "non-deterministic collation instead."
                     ),
                     obj=PostgresCIFieldsModel._meta.get_field("ci_char"),
-                    id="fields.W905",
+                    id="fields.E905",
                 ),
-                checks.Warning(
-                    "django.contrib.postgres.fields.CIEmailField is deprecated. "
-                    "Support for it (except in historical migrations) will be removed "
-                    "in Django 5.1.",
+                checks.Error(
+                    "django.contrib.postgres.fields.CIEmailField is removed except for "
+                    "support in historical migrations.",
                     hint=(
                         'Use EmailField(db_collation="…") with a case-insensitive '
                         "non-deterministic collation instead."
                     ),
                     obj=PostgresCIFieldsModel._meta.get_field("ci_email"),
-                    id="fields.W906",
+                    id="fields.E906",
                 ),
-                checks.Warning(
-                    "django.contrib.postgres.fields.CITextField is deprecated. Support "
-                    "for it (except in historical migrations) will be removed in "
-                    "Django 5.1.",
+                checks.Error(
+                    "django.contrib.postgres.fields.CITextField is removed except for "
+                    "support in historical migrations.",
                     hint=(
                         'Use TextField(db_collation="…") with a case-insensitive '
                         "non-deterministic collation instead."
                     ),
                     obj=PostgresCIFieldsModel._meta.get_field("ci_text"),
-                    id="fields.W907",
+                    id="fields.E907",
                 ),
-                checks.Warning(
-                    "Base field for array has warnings:\n"
-                    "    django.contrib.postgres.fields.CITextField is deprecated. "
-                    "Support for it (except in historical migrations) will be removed "
-                    "in Django 5.1. (fields.W907)",
+                checks.Error(
+                    "Base field for array has errors:\n"
+                    "    django.contrib.postgres.fields.CITextField is removed except "
+                    "for support in historical migrations. (fields.E907)",
                     obj=PostgresCIFieldsModel._meta.get_field("array_ci_text"),
-                    id="postgres.W004",
+                    id="postgres.E001",
                 ),
             ],
         )
diff --git a/tests/postgres_tests/fields.py b/tests/postgres_tests/fields.py
index 1565b5ed43..c2513fca0c 100644
--- a/tests/postgres_tests/fields.py
+++ b/tests/postgres_tests/fields.py
@@ -7,9 +7,6 @@ import enum
 from django.db import models
 
 try:
-    from django.contrib.postgres.fields import CICharField  # RemovedInDjango51Warning.
-    from django.contrib.postgres.fields import CIEmailField  # RemovedInDjango51Warning.
-    from django.contrib.postgres.fields import CITextField  # RemovedInDjango51Warning.
     from django.contrib.postgres.fields import (
         ArrayField,
         BigIntegerRangeField,
@@ -47,9 +44,6 @@ except ImportError:
 
     ArrayField = DummyArrayField
     BigIntegerRangeField = models.Field
-    CICharField = models.Field  # RemovedInDjango51Warning.
-    CIEmailField = models.Field  # RemovedInDjango51Warning.
-    CITextField = models.Field  # RemovedInDjango51Warning.
     DateRangeField = models.Field
     DateTimeRangeField = DummyContinuousRangeField
     DecimalRangeField = DummyContinuousRangeField
diff --git a/tests/postgres_tests/migrations/0002_create_test_models.py b/tests/postgres_tests/migrations/0002_create_test_models.py
index 011a0d729b..5538b436ad 100644
--- a/tests/postgres_tests/migrations/0002_create_test_models.py
+++ b/tests/postgres_tests/migrations/0002_create_test_models.py
@@ -3,9 +3,6 @@ from django.db import migrations, models
 from ..fields import (
     ArrayField,
     BigIntegerRangeField,
-    CICharField,
-    CIEmailField,
-    CITextField,
     DateRangeField,
     DateTimeRangeField,
     DecimalRangeField,
@@ -290,23 +287,6 @@ class Migration(migrations.Migration):
             options=None,
             bases=None,
         ),
-        # RemovedInDjango51Warning.
-        migrations.CreateModel(
-            name="CITestModel",
-            fields=[
-                (
-                    "name",
-                    CICharField(primary_key=True, serialize=False, max_length=255),
-                ),
-                ("email", CIEmailField()),
-                ("description", CITextField()),
-                ("array_field", ArrayField(CITextField(), null=True)),
-            ],
-            options={
-                "required_db_vendor": "postgresql",
-            },
-            bases=None,
-        ),
         migrations.CreateModel(
             name="Line",
             fields=[
diff --git a/tests/postgres_tests/models.py b/tests/postgres_tests/models.py
index 05f2732fb8..a97894e327 100644
--- a/tests/postgres_tests/models.py
+++ b/tests/postgres_tests/models.py
@@ -3,9 +3,6 @@ from django.db import models
 from .fields import (
     ArrayField,
     BigIntegerRangeField,
-    CICharField,
-    CIEmailField,
-    CITextField,
     DateRangeField,
     DateTimeRangeField,
     DecimalRangeField,
@@ -119,14 +116,6 @@ class Character(models.Model):
     name = models.CharField(max_length=255)
 
 
-# RemovedInDjango51Warning.
-class CITestModel(PostgreSQLModel):
-    name = CICharField(primary_key=True, max_length=255)
-    email = CIEmailField()
-    description = CITextField()
-    array_field = ArrayField(CITextField(), null=True)
-
-
 class Line(PostgreSQLModel):
     scene = models.ForeignKey("Scene", models.CASCADE)
     character = models.ForeignKey("Character", models.CASCADE)
diff --git a/tests/postgres_tests/test_citext.py b/tests/postgres_tests/test_citext.py
deleted file mode 100644
index 2abb56b39f..0000000000
--- a/tests/postgres_tests/test_citext.py
+++ /dev/null
@@ -1,91 +0,0 @@
-# RemovedInDjango51Warning.
-"""
-The citext PostgreSQL extension supports indexing of case-insensitive text
-strings and thus eliminates the need for operations such as iexact and other
-modifiers to enforce use of an index.
-"""
-from django.db import IntegrityError
-from django.utils.deprecation import RemovedInDjango51Warning
-
-from . import PostgreSQLTestCase
-from .models import CITestModel
-
-
-class CITextTestCase(PostgreSQLTestCase):
-    case_sensitive_lookups = ("contains", "startswith", "endswith", "regex")
-
-    @classmethod
-    def setUpTestData(cls):
-        cls.john = CITestModel.objects.create(
-            name="JoHn",
-            email="joHn@johN.com",
-            description="Average Joe named JoHn",
-            array_field=["JoE", "jOhn"],
-        )
-
-    def test_equal_lowercase(self):
-        """
-        citext removes the need for iexact as the index is case-insensitive.
-        """
-        self.assertEqual(
-            CITestModel.objects.filter(name=self.john.name.lower()).count(), 1
-        )
-        self.assertEqual(
-            CITestModel.objects.filter(email=self.john.email.lower()).count(), 1
-        )
-        self.assertEqual(
-            CITestModel.objects.filter(
-                description=self.john.description.lower()
-            ).count(),
-            1,
-        )
-
-    def test_fail_citext_primary_key(self):
-        """
-        Creating an entry for a citext field used as a primary key which
-        clashes with an existing value isn't allowed.
-        """
-        with self.assertRaises(IntegrityError):
-            CITestModel.objects.create(name="John")
-
-    def test_array_field(self):
-        instance = CITestModel.objects.get()
-        self.assertEqual(instance.array_field, self.john.array_field)
-        self.assertTrue(
-            CITestModel.objects.filter(array_field__contains=["joe"]).exists()
-        )
-
-    def test_lookups_name_char(self):
-        for lookup in self.case_sensitive_lookups:
-            with self.subTest(lookup=lookup):
-                query = {"name__{}".format(lookup): "john"}
-                self.assertSequenceEqual(
-                    CITestModel.objects.filter(**query), [self.john]
-                )
-
-    def test_lookups_description_text(self):
-        for lookup, string in zip(
-            self.case_sensitive_lookups, ("average", "average joe", "john", "Joe.named")
-        ):
-            with self.subTest(lookup=lookup, string=string):
-                query = {"description__{}".format(lookup): string}
-                self.assertSequenceEqual(
-                    CITestModel.objects.filter(**query), [self.john]
-                )
-
-    def test_lookups_email(self):
-        for lookup, string in zip(
-            self.case_sensitive_lookups, ("john", "john", "john.com", "john.com")
-        ):
-            with self.subTest(lookup=lookup, string=string):
-                query = {"email__{}".format(lookup): string}
-                self.assertSequenceEqual(
-                    CITestModel.objects.filter(**query), [self.john]
-                )
-
-    def test_citext_deprecated(self):
-        from django.contrib.postgres.fields import CIText
-
-        msg = "django.contrib.postgres.fields.CIText mixin is deprecated."
-        with self.assertRaisesMessage(RemovedInDjango51Warning, msg):
-            CIText()
diff --git a/tests/runtests.py b/tests/runtests.py
index 2eb7490170..5d138ffb0e 100755
--- a/tests/runtests.py
+++ b/tests/runtests.py
@@ -245,13 +245,6 @@ def setup_collect_tests(start_at, start_after, test_labels=None):
     settings.LOGGING = log_config
     settings.SILENCED_SYSTEM_CHECKS = [
         "fields.W342",  # ForeignKey(unique=True) -> OneToOneField
-        # django.contrib.postgres.fields.CICharField deprecated.
-        "fields.W905",
-        "postgres.W004",
-        # django.contrib.postgres.fields.CIEmailField deprecated.
-        "fields.W906",
-        # django.contrib.postgres.fields.CITextField deprecated.
-        "fields.W907",
     ]
 
     # Load all the ALWAYS_INSTALLED_APPS.