Post deletion when the thread is deleted is already handled by django. No need to implement it manually

boards/models/thread.py

@@ -194,16 +194,6 b' class Thread(models.Model):'
 
         return self.get_opening_post().pub_time
 
-    def delete(self, using=None):
-        """
-        Deletes thread with all replies.
-        """
-
-        for reply in self.get_replies().all():
-            reply.delete()
-
-        super(Thread, self).delete(using)
-
     def __str__(self):
         return 'T#{}/{}'.format(self.id, self.get_opening_post_id())