If you want to know about the steps to smoothly clear search history on Facebook app then proceed to profile page and click on activity log button below your profile photo. Now, click on filter at the top of the screen. Scroll down to find and choose search history. After that, you need to clear search history on Facebook app by clicking on clear searches and then tap to confirm. Lastly, to delete the entries, choose the icon next to the entry in question and choose to delete.