Hard Reset SAMSUNG G750K Galaxy Mega 2

First method:

1. In order to turn off the cell phone hold down the Power button for a short while.
2. After that, press and hold together: Volume Up + Home + Power button for a couple of seconds.
3. Release held keys when the Samsung Logo appears on the screen.
4. Then select from Recovery Mode menu "wipe data / factory reset" using Volume buttons to navigate and Power button to confirm.
   
5. Choose "Yes -- delete all user data" to confirm the whole operation.
6. After that select option "reboot system now".
7. Well done! The hard reset has just been performed.

Second method:

1. Start by turninng on the device.
2. From the Home Screen go to Menu and then to Settings.
3. Tap Backup & Reset and then Factory data reset.
4. In the next step choose Reset device.
5. To confirm your choice select Erase everything.
6. That's all.

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