MR4Y

You can't. Once you joined you sold your soul to Rosewind. You are bound here for ever. 

Being serious, there is no delete account option, but you can just say you dont want to come anylonger and just dont come. If you ever change your mind, you still have that same account 

This may help you:

Really? Who can code such a lackluster and feature crippled forum system (IPBoard) and still be allowed to live?