Fortunately you can remove those searches, either individually, or all at once.
Go the drop down arrow near the top of your Facebook page.
Click on "activity log".
Click on the more link.
Click on the search link
There you will see everything you have searched. If you want to delete just one or two you can choose the delete to the right of each search. If you want to get rid of everything there is a clear searches link at the top.