I'm the only owner and can't leave my organization

An organization always needs at least one owner, so the last remaining owner can't be demoted, removed, or leave the organization — this is intentional, not a bug.

To leave, first promote another member to Owner from Team Members (only an existing owner can do this), then leave normally from the Organization page.

If you're leaving the organization entirely and no one else should take over, contact support instead of trying to force it through the portal.