You can delete it completely if there's no one a fan of it, because if you delete it and there's fans on it the first person that joined will be given the ownership of the club and be their problem to deal with keeping the club up and running.
You delete it by going to your clubs and there will be a blueish grey "X" you push it you unfan the club but like I said if there's fans already in it the first person that joined will get ownership and it won't delete the club unless there's no one (besides yourself) that is a fan and you unfan the club, it will delete the club, there's no other way to delete the club permanently with other fans in it.
