Hard Reset SAMSUNG G710 Galaxy Grand 2

First method:

1. Turn off your phone.
   
2. Press and hold together Volume Up + Home button + Power button.
   
3. Then release them, when you see logo Samsung.
4. Choose option from the menu "wipe data/factory reset", using Volume buttons, and confirm with Power button.
   
5. Next select "yes" with Volume Down and confirm with Power button.
   
6. After this operation select "reboot system now".
   

Second method:

1. Switch on your cell phone.
   
2. Then navigate to Settings -> User and Backup -> Factory Data Reset.
3. Accept all information on your screen.
4. Success!

Third method:

1. Power on the phone.
   
2. Dial or press number to call: *2767*3855#
3. That number code will force format on device.

WARNING !
Hard Reset will erase all of your data
All described operations you are doing at your own risk.