Microsoft's PC e-mail client Outlook 2007 includes a feature called Instant Search, which allows you to quickly search multiple mailboxes for messages based on search criteria. By default, Outlook keeps a history of all the searches you perform. However, if you do not want to keep a history of your searches, you can disable the feature and delete your current Outlook search history.
Launch Microsoft Outlook 2007 and log in to your e-mail account.
Go to the "Tools" menu at the top of the window and click on "Instant Search."
Click on the "Search Options" button to open another pop-up window with additional search settings.
Uncheck the box next to "Display search results as I type when possible."
Hit the "OK" button to save the settings. Outlook will now stop keeping a history of your searches and will automatically delete all existing history data.