Hey Axel43, To erase my search history on Facebook, follow these steps:
Firs, tap in the bottom right of Facebook, then tap your name. Next, tap below your profile picture, then tap Activity Log. Then, scroll down to Logged Actions and Other Activity, then tap View Logged Actions. Next, tap Filters at the top, then tap Categories. Then, tap Search History. Finally, at the top, tap Clear Searches.