You are stuck, eternity.
HOW DO I LEAVE A CLUB WHEN I AM BANNED?

I WANT TO LEAVE THE CLUB THEN JOIN HOW?
????
If you are banned, you're not actually in the club. So it doesn't matter.
If you suddenly got notifications from that club, it's probably because you are in the beta and a new notification system was implemented. Just clear out the alerts and you won't get any more from that club.
https://www.chess.com/clubs/forum/view/launching-new-web-notifications-system
You might mention it in that topic, if that is your issue. That's something they may want to address.
I WANT TO LEAVE THE CLUB THEN JOIN HOW?
????