http://code.google.com/p/googlehacks/
OR
file and search
Deleting search history from the Google home page search box
In Internet Explorer
The search history that displays in the search box on the Google homepage is stored by your browser, not by Google. You can clear the history or disable this feature entirely by following these steps:
You can also delete individual entries from your search history by using the Down arrow key to highlight a previous search and then pressing the Delete key.
In Firefox
As with Internet Explorer, you can also clear the search history or disable the feature in Firefox.
Another way to very quickly clear the search history is to place your cursor in the search box, right click and select “clear search history.” This is faster for on-the-fly clearing.
You can also delete individual entries from your search history by using the Down arrow key to highlight a previous search and then pressing the Shift-Delete key.
Deleting search history from the Google Toolbar
The Google Toolba Internet Explorer also retains the search history if you let it. Clearing the current search history or disabling the feature in the browser does not affect the Google Toolbar. You have to do it in the Toolbar separately.
To completely disable your Toolbar’s search history
To simply clear the current search history:
Deleting search history from the Googlebar Firefox extension
The Google Toolbar has not yet been written for Firefox, but there is an extension called Google Toolbar provides a similar function. It also retains the search history. The difference is that it does not automatically place everything in a drop down list for the user to see. But, it is there to view with the click of a check mark at the right of the search box.
To completely disable Googlebar’s search history:
To simply clear the current search history: