Hard Reset SAMSUNG E300K Galaxy S4

First method:

1. Turn on your device.
   
2. Now goto Settings -> User and Backup -> Factory Data Reset.
3. Confirm all information on your screen.
4. Done!

Second method:

1. Switch off the cell phone.
   
2. Then hold and press 3 keys: Volume Up + Home button + Power button.
   
3. Next release all keys, when Samsung logo appear.
4. Select option "wipe data/factory reset" using Volume Down button, and confirm withPower button.
   
5. Choose "Yes -- delete all user data" form the menu, and confirm with Power button.
   
6. After that select "reboot system now".
   

Third method:

1. Power on the phone.
   
2. Next just type thid secret code: *2767*3855#
3. That number code will force format on device.

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