>I am having trouble figuring out how to delete a persons cashe (history) in their browser. The reason I want to do this is because I am running a secure site, and I do not want them to be able to view where they have been in their history. I have already blocked their location bar and their status bar.

Why would that make a difference? I would get pissed if you did that to my system - that's hacking.

You need to have a mechanism to only allow authenticated users into the sensitive areas of your site. Then it would not matter if they knew - since they would not be able to get back in to those pages.