We don't have a way to unregister. But you could go to your control panel and change your email address to some non-existent address. When you change your email, we automatically send you a confirmation email with a link for you to click. You won't be able to use your account until you click on that link. But you won't be able to click on the link since you did not get it. Because we will now an incorrect email address, we can never contact you.