it seems that the bug where you couldnt remove warnings of users not in the guild anymore seems to have been fixed when moving over to the new version of discord.py

cogs/admin.py

@@ -10,8 +10,8 @@ class Admin():
 	"""
 	Admin Commands for those admins
 	"""
-	def __init__(self, Bot):
-		self.bot = Bot
+	def __init__(self, bot_client):
+		self.bot = bot_client
 		self.slow_mode = False
 		self.slow_mode_channels = {}
 		self.users = {}
@@ -174,5 +174,5 @@ class Admin():
 				return await ctx.send("Could not find user in warning list.")
 
 
-def setup(Bot):
-	Bot.add_cog(Admin(Bot))
+def setup(bot_client):
+	bot_client.add_cog(Admin(bot_client))