From AB FAQ's
Question Author
How do I un-register from The AnswerBank?
Send an email to the AnswerBank Editor asking to be un-registered. You will be unregistered from The AnswerBank so that you no longer receive emails from us and that your account cannot be accessed. We do, however, have a policy of retaining anything you have posted during your time with us. We believe that your contribution to The AnswerBank is important and the answers and questions you posted could help someone out in the future.
11:55 Tue 07th Dec 2010
As such you'll only un-register, and apart from asking
Ab Editor to delete yopur posts, then the above is the only way, but all your Q&A's remain the property of The AnswerBank.