diff --git a/telethon/tl/custom/dialog.py b/telethon/tl/custom/dialog.py
index 39e01668..2297da97 100644
--- a/telethon/tl/custom/dialog.py
+++ b/telethon/tl/custom/dialog.py
@@ -99,6 +99,10 @@ class Dialog:
     async def delete(self):
         if self.is_channel:
             await self._client(functions.channels.LeaveChannelRequest(self.input_entity))
+        elif self.is_group:
+            await self._client(functions.messages.DeleteChatUserRequest(self.entity.id,
+                                                                        types.InputPeerSelf()))
+            await self._client(functions.messages.DeleteHistoryRequest(self.input_entity, 0, just_clear=False))
         else:
             await self._client(functions.messages.DeleteHistoryRequest(self.input_entity, 0))