Follow the steps mentioned below and learn about how to app. On your iPhone, open the Facebook application. At the upper-right hand side of the screen, click on the search icon. Click on edit where it says recent searches to clear the search history on the iPhone app. Lastly, at the top of the activity log, click the to clear searches option to clear Facebook search history on the iPhone device. These are the steps that users need to follow to clear the search history on the iPhone device.