Hard Reset SAMSUNG Galaxy Tab S 8.4 WiFi

First method:

1. Turn off your tablet by holding the Power key.
   
2. Now press and hold Volume Up + Home button + Power button.
   
3. After few seconds you will see Recovery mode menu.
4. From this menu choose option "wipe data / factory reset" using Volume buttons to scroll and Power button to confirm your choice.
   
5. Next select option "Yes -- delete all user data".
   
6. Then accept option "reboot system now".
   
7. Well done!

Second method:

1. Power on the tablet.
   
2. Next goto Menu -> Settings -> Backup & reset -> Reset device -> Erase everything.
3. Then wait until your device resets and reboots.
4. Good job!

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