u can't I'm afraid. You'll just have to make do with making your page blank, saying you're no longer a memeber and never coming back. But if you're really determined to be deleted u can ask for people to meld u because if enough do I think u should be deleted.
u shouldn't really care as you'd be dead but u could get someone to change your motto to the fact you're deceased of something. Hope it's alrigt if i answered that.