Like others already said: make it suck. Go into your Joker arc and become the edgelord. You build it and you can destroy it. But you can’t just go full psycho over night. Make it look like you are becoming a power hungry mod with a napoleon complex over the course of a couple of weeks. As soon as some users start their own subreddit start linking there (preferably by making fun of them to stay in character) so the migration keeps going. While this is happening, ban the few contributing users that are still there.
When everything is burned down, post a dick pic on r/mentalhealth, log off and never look back.
PS: Bonus points if you document everything and release it on YouTube.
Chad it is then.