If you need to completely restore Samsung Galaxy S4 you can restore it back to factory settings.
This way you will delete absolutely everything – good if you need to sell phone etc.
1 – Switch S4 phone off.
2 – Hold down the Power + Volume Up + Home buttons at the same time till it vibrates and you see this screen
3 – Use volume key down to select “Wipe Data/Factory Reset
4 – Use power button to confirm selected option
5 – Select “YES” from next menu
6 – Use power button to confirm selected option (“Yes”)
7 – Select “power down”
Done!