diff --git a/changelog.d/12018.removal b/changelog.d/12018.removal
new file mode 100644
index 0000000000000000000000000000000000000000..e940b62228acebfc59aea63490806f4cff9e61c1
--- /dev/null
+++ b/changelog.d/12018.removal
@@ -0,0 +1 @@
+Drop support for [MSC3283](https://github.com/matrix-org/matrix-doc/pull/3283) unstable flags now that the stable flags are supported.
diff --git a/synapse/config/experimental.py b/synapse/config/experimental.py
index 12b5638cf8b7f7e52cc6aebccff657c7d09afe9b..bcdeb9ee232d70ce7c8905a4b3ca0140406c4127 100644
--- a/synapse/config/experimental.py
+++ b/synapse/config/experimental.py
@@ -41,9 +41,6 @@ class ExperimentalConfig(Config):
         # MSC3244 (room version capabilities)
         self.msc3244_enabled: bool = experimental.get("msc3244_enabled", True)
 
-        # MSC3283 (set displayname, avatar_url and change 3pid capabilities)
-        self.msc3283_enabled: bool = experimental.get("msc3283_enabled", False)
-
         # MSC3266 (room summary api)
         self.msc3266_enabled: bool = experimental.get("msc3266_enabled", False)
 
diff --git a/synapse/rest/client/capabilities.py b/synapse/rest/client/capabilities.py
index 6682da077a3ea527b26216189c0916f62a78529d..e05c926b6f06be1b39d5a7afbc82fd4aade29448 100644
--- a/synapse/rest/client/capabilities.py
+++ b/synapse/rest/client/capabilities.py
@@ -72,20 +72,6 @@ class CapabilitiesRestServlet(RestServlet):
                 "org.matrix.msc3244.room_capabilities"
             ] = MSC3244_CAPABILITIES
 
-        # Must be removed in later versions.
-        # Is only included for migration.
-        # Also the parts in `synapse/config/experimental.py`.
-        if self.config.experimental.msc3283_enabled:
-            response["capabilities"]["org.matrix.msc3283.set_displayname"] = {
-                "enabled": self.config.registration.enable_set_displayname
-            }
-            response["capabilities"]["org.matrix.msc3283.set_avatar_url"] = {
-                "enabled": self.config.registration.enable_set_avatar_url
-            }
-            response["capabilities"]["org.matrix.msc3283.3pid_changes"] = {
-                "enabled": self.config.registration.enable_3pid_changes
-            }
-
         if self.config.experimental.msc3440_enabled:
             response["capabilities"]["io.element.thread"] = {"enabled": True}