Apple iPhone 6

Find "Touch ID & Passcode"

Press Settings.

Find "Touch ID & Passcode"

Press Touch ID & Passcode.

Select option

Select one of the following options:
Turn on use of phone lock code, go to 2a.
Turn off use of phone lock code, go to 2b.

2a - Turn on use of phone lock code

Press Turn Passcode On.

2a - Turn on use of phone lock code

If you've already added a fingerprint:
Press Keep or Delete.

2a - Turn on use of phone lock code

Key in a phone lock code of your own choice.
Key in the same phone lock code again.
Press Require Passcode.

2a - Turn on use of phone lock code

Press Immediately or the required period.

2a - Turn on use of phone lock code

Press Back.

2b - Turn off use of phone lock code

Press Turn Passcode Off.
Key in your phone lock code.

Return to the home screen

Press the Home key to return to the home screen.