Hi there, Are you still encountering this issue? To leave a Clan as the Clan Founder, you must first designate another Clan member to be the Clan Founder. Only Clan Admins can be designated Clan Founders, so if you do not have any Clan Admins, you will have to promote a Clan member to Admin and then designate them as the Clan Founder. Once you are no longer Clan Founder, you can leave the Clan by choosing the Leave Clan option on the Clan profile.
Can you kick them from the clan instead? Then it should allow you to leave as you'll be the last one.