click on your clubs on your profile... then you'll have the list of clubs you're in, then you click unsubscribe and its done ^^ But hey... u dont have to insult JB on the JB spot, fans will obviously hate you a lot ;)
On your profile, go to your clubs. Locate the Justin Bieber club, and there should be a word next to it that says "unsubscribe". Click that and it should remove you. Hope it helps!!