Tap on Backup & Reset .
This method works if your OPPO F3 is not frozen, not password-locked, and you can navigate the menu. How to Hard Reset OPPO F3
Select Factory Data Reset (sometimes labeled Erase All Data ). Tap on Backup & Reset
Performing a hard reset on your OPPO F3 is a powerful way to resolve persistent software glitches, remove forgotten screen locks, or wipe personal data before selling the device. remove forgotten screen locks
Ideally, never. Only reset as a last resort. Frequent hard resets can wear down the internal eMMC storage chip over time.