Hard Reset SAMSUNG T2105 Galaxy Tab 3.0 Kids

First method:

1. Start by switching off your tablet by holding the Power key for a short while.
2. Now press and hold together: Volume Up + Home button + Power button.
3. Release held keys when an Android Icon appears on the screen.
4. Then select "wipe data / factory reset" using Volume buttons to navigate and Power buttonto confirm.
   
5. Afterwards choose "Yes -- delete all user data" to confirm whole operation.
6. In order to restart the device select "reboot system now".
7. Well done!

Second method:

1. If the display is off, press the Power to turn it back on.
2. Afterwards go to Settings and then to Backup & reset.
3. Tap Reset Devive. 
4. Choose Erase Everything if you are sure you want to clear all your data. 
5. Select OK to confirm the whole operation.
6. Well done!

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