1. Find "Sign-in options"
Slide your finger downwards starting from the top of the screen.
Press All settings.
Press Personalisation.
Press Lock screen.
Press Sign-in options.
2. Turn on use of phone lock code
Press Add.
Press New PIN and key in the required phone lock code.
Press Confirm PIN and key in the phone lock code again.
Press OK.
3. Turn off use of phone lock code
Press Remove.
Press Remove.
4. Return to the home screen
Press the Home key to return to the home screen.