Hard Reset SAMSUNG i727 Galaxy S II Skyrocket

First method:

1. First from the home screen, press the Menu key, and then tap Settings.
   
2. Then scroll to and tap Privacy.
3. Next tap Factory data reset.
4. Afterwards Tap Reset phone.
   * NOTE: Tap to check Format USB Storage to remove all saved media and applications from an inserted Micro SD memory card.
   * If security is enabled, enter your unlock PIN, password, or pattern.
5. Now select Erase Everything.

Second method:

1. Make sure, that your phone is off.
2. Next press and hold Volume Up + Volume Down + Power button.
   
3. When Samsung Splash Screen appear, then quickly let go of the buttons.
4. Now you will see Recovery Mode menu, where select "Wipe data/factory reset" usingVolume buttons to scroll, and Home button to confirm.
   
   
5. Select "yes" and press Home button.
   
6. After format, press Home button to accept option "reboot system now".
   

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