Yeah it's like trying to delete a torrent that you created lol, deleting stuff from the Internet is not so easy. Even websites that claim to allow you to delete stuff may still be backed up by The Wayback Machine or similar, or even just a random user who liked your post and downloaded it.
I would like improvements here, but you should probably still be careful about anything you post if you're worried about being able to delete it, no matter what site you're on.