To leave Curezone just log off and don't come back, you are not under contract or anything.
You can manually delete your posts using the edit feature, then use the privacy manager to hide your username. Or, if you think you might have posted something that will help others, just change your username using the privacy manager and leave the posts. It will be up to you to do this, its asking a lot of the Webmaster or moderators to have to do this for you.
Edit: I am sorry to see you go, I had to find out who you were since your number sounded so familiar. I am sorry some people were not very nice to you. There seems to be a lot of trolls and possibly imposters stirring up trouble right now. Frankly, I smell a rat, a rat with $$$$ on his mind.