Open the Facebook app on your mobile
Tap the menu icon
Go to Settings & privacy
Tap Settings
Tap Accounts Center
Tap Personal details
Tap Account ownership and control
Tap Deactivation or deletion
Select the Facebook account
Tap Delete account
Tap Continue
Follow the on-screen prompts
Enter your password if asked
Confirm deletion
Download your data first if you want to keep a copy
Log out after submitting the deletion request