diff --git a/django/db/backends/mysql/schema.py b/django/db/backends/mysql/schema.py
index ef4ccf51db..3cdc53c858 100644
--- a/django/db/backends/mysql/schema.py
+++ b/django/db/backends/mysql/schema.py
@@ -21,9 +21,6 @@ class DatabaseSchemaEditor(BaseDatabaseSchemaEditor):
 
     sql_delete_index = "DROP INDEX %(name)s ON %(table)s"
 
-    alter_string_set_null = 'MODIFY %(column)s %(type)s NULL;'
-    alter_string_drop_null = 'MODIFY %(column)s %(type)s NOT NULL;'
-
     sql_create_pk = "ALTER TABLE %(table)s ADD CONSTRAINT %(name)s PRIMARY KEY (%(columns)s)"
     sql_delete_pk = "ALTER TABLE %(table)s DROP PRIMARY KEY"