1. Turn off the deivce.
2. Press and hold the Power, Volume Up and Home buttons.
3. When Recovery mode appear,
use the Volume keys to navigate and Power button to select an option.
4. Select 'wipe data factory reset' to hard reset.
5. Select 'reboot system now' to restart the phone.
★ If you want to clear app data cache too, choose 'wipe cache partition'