[Cleanup] Delete command message when using [p]cleanup self (#4640)

* delete command message

* only delete command if can_mass_purge

redbot/cogs/cleanup/cleanup.py

@@ -579,6 +579,8 @@ class Cleanup(commands.Cog):
             before=ctx.message,
             delete_pinned=delete_pinned,
         )
+        if can_mass_purge:
+            to_delete.append(ctx.message)
 
         if ctx.guild:
             channel_name = "channel " + channel.name