There isn't really a way to hide yourself. I live by the mantra that anything you post online will be out there forever.
Even if you could hide yourself in the built in site search good luck hiding from Google. As an aside, using google's site specific search usually works better than the built in search. For example, if I was looking for all my posts I could type:
FireDancer site:disboards.com
and google will search the entire site starting at the disboards.com root.