how do I delete google and yahoo search bar history?

My wife doesnt like me gambling online so I have to go ahead and hide it from her. Well she is smart enough to know that if I delte the address bar history then I was probably at a poker site so I cant do that anymore. SO now I am using the google and yahoo search bars to go to the sites but I cant figure out how to stop it from stying in that history and how to delete it. You know when you click on the search area and you can see all the places that have been searched. How do I delete this? Thanks