This article explains how to delete your Facebook account on iPhone and what you need to do before deleting it. It also describes the key differences between deleting and deactivating.
How do I delete a Facebook account on iPhone?
Once you've disconnected your apps and downloaded any data you want to keep, you can permanently delete your Facebook account using the Facebook app for iPhone. (Scroll down for more information on how to do this.)
Open the Facebook app on your iPhone and tap Menu (three lines) in the bottom right corner of the screen.
Tap Settings & Privacy, then tap Settings.
