Selam aleykum
This depends on which internet browser you use.
For IE7: On top left click Tools -> Internet options -> "general" tab -> browsing history: "Delete" -> Delete Forms
For firefox: On top left click Edit -> preferences -> "Privacy" tab -> private data: "settings" -> Make sure the following are ticked: "browsing history; cookies; saved form information; cache" -> ok -> then in previous window click: Private data: "clear now"
If this doesn't work, there's an alternative, first run windowsexplorer and go to:
c:\Documents and settings\
[the name of your useraccount]\ snoop around a bit the files that keep this information should be in that folder somewhere. I forgot the exact location and I can't go check since I don't have windows installed. But it's probably in a directory like \IE7\history or something like that. If you can't find it, just delete the whole IE directory (don't worry, windows will build a new one so there's no harm).
If you don't have access to any of those things, then there's no way to delete it. For future reference, maybe try setting the options of the explorer so that it doesn't store forms before you start searching. You could also use lesser known search engines. Here's a list:
http://win3.1.freeservers.com/psearch.htm That way at least your search querrys won't pop up every time someone types in something in Google. And you can only get burned if someone actually starts checking up on the saved forms.