Hard Reset SAMSUNG I8160 Galaxy Ace 2

First method:

1. First, turn off the phone by using the Power button.
2. Now press and hold together:  Volume Up + Home button + Power button, until you see Samsung logo.
3. Then select from Recovery Mode menu "wipe data / factory reset" using Volume buttons to navigate and Home button to confirm.
   
4. Choose "Yes -- delete all user data" to confirm the whole operation.
5. After that select option "reboot system now".
6. 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 Privacy and then Reset device.
4. To confirm your choice select Erase everything.
5. That's all.

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