If you mean your internet history, if you check your browser history, the websites you want to delete should be deleted, or if you start typing them in on the browser bar, the browser does not predict where you are trying to go by listing the website in a list of suggestions that appears below the browser bar.

Go into your internet history (varies by browser) check and see if the websites are listed or not. What browser are you using? Internet Explorer, Chrome, Firefox, Safari etc...

Push CTRL + H and check to see, a good way to remove traces of browsing past and other temporary files is by using a program called ccleaner.

http://www.piriform.com/ccleaner

Download it and use default options, its very easy