To clear the search box history from the google main page eg www.google.com you have to clear it from your computer as that is where it is stored ,here is how to do it.
For Internet Explorer 6 do the following:
Go to the
Tools menu and select
Internet Options then go to the
Content tab click the
AutoComplete button and then click the
Clear Forms button ,click on
Apply and then
OK to close the Internet Explorer options menu.
For Internet Explorer 7 do the following :
Go to the
Tools menu and select
Delete Browsing History then click the
Delete forms button ,click
Yes in the confirmation window when finished click on
Close.
For FireFox do the following:
Go to the
Tools menu then select
Clear Private Data now select
Saved Form and Search History and click the
Clear Private Data Now button.
That is it your history has been cleared.