Unlocking with the fingerprint sensor and setting up automatic unlocking make it easier to keep your phone secure and minimise when you need to enter your PIN, pattern or password. But sometimes you need to trade convenience for more security. You can temporarily tighten locks and prevent lock screen notifications.
Swipe down from the top of the screen twice, then touch 
Or, press and hold the power + volume up buttons simultaneously, then tap Power off.
Touch Lockdown.
Your fingerprint sensor and automatic unlock settings are disabled and notifications won't be displayed on your lock screen.