Pages and links that you visit on the web are stored in temporary folders on your hard drive. People may be able to see which sites on the internet you have visited by viewing the files in these folders. In order to cover your tracks you need to:
Internet Explorer 6 
When in Internet Explorer 6, go to the menu bar at the top of the page. It looks like this:
Select Tools, go to the bottom of the dropdown menu and select Internet Options.

Click Delete Files... and check the Delete all offline content box and then click OK.

Click on the Clear History button. Click on Yes to delete your history of visited websites

Finally, click OK to close the Internet Options button.
