Click on your profile picture first, in the top right corner.
Tap on Settings and Privacy, then click on Settings.
Click on the personal details on the left menu.
Again, go to the personal details if it is not open.
Tap on the Account ownership and control.
Finally, choose the second option, Deactivation or deletion, to temporarily delete your Facebook profile. However, if you do not open for a certain period, then your account is permanently deleted.
Through Mobile
Tap on the three dots (Menu icon) at the top right corner.
Scroll down and choose Settings & Privacy, then tap Settings.
Tap "Profile Access and Control," then tap "Deactivation and Deletion".