The Facebook search tool keeps note of what you've looked for so you can return to commonly visited pages. However, what and who you look for on Facebook is completely private. A record of the items you look for on Facebook is kept in your activity log. To begin, open the Facebook app on your smartphone.Then, in the upper right corner of Facebook, tap (three horizontal lines).Tap your name on the new page. Below your profile photo, press Menu (three dots).Now, choose one of the alternatives provided. Select the Activity Log option. Hit Menu (three dots) next to the search you wish to erase on the new page, then tap Delete. Here are the steps on how to delete search history on facebook app.