Sorry to hear that bro. I believe once your clan was hacked, there's nothing you can do about it. Try to invite one more on your clan and promote him/her to be the commander.
As far as I know you can still leave the clan through in game. It's under barracks > clan details > leave clan.
Are you the clan leader? I believe you can still leave your clan. Clan leaders can leave their clan once there is no other member left but him.