In case the problem is where this option is found: On your league page click/tap the 3 dots on the upper left corner and then Leave. In case it's another problem more information is needed.
OK, I flagged the support to take a look. In the meantime trying to join another league directly, or asking the host of your current league to try to kick your team might be worth testing.
I've already tried joining another league directly, but that doesn't work either. This league doesn't have an administrator; I left a message there asking them to kick me out.
The worst part is that I can't train either the driver or the mechanics; the message keeps appearing: THIS IS BLOCKED BECAUSE YOUR TEAM IS IN A LIVE RACE EVENT.
I'm still having the same problem....same message that I'm in an event.
Please, if you could, remove my account from this league, because I can't. This is my best account with several DTs and DCs. Help!!!!!
OK, I see you're in an official iGP league, and also noticed the calendar of that league is messed up. I suppose those races scheduled to a date in the past, but appear as still have to be run in the league schedule are the culprit of those issues. Escalated it directly to team Discord.