Luckily for you can erase your Facebook search history. To do this, login your Facebook account, click on the upside-down triangle in the top-right corner, and click Activity Log. The Activity Log is where Facebook tracks your actions within the site
In the left column of the Activity Log, under “Photos, Likes and Comments,” click More. Then scroll down and click the “Search” link.
To clear every search without the hassle of sifting through years of individual entries, click the “Clear Searches” link located at the top-right of the list.