Unlocking with the fingerprint sensor and setting up automatic unlocking make it easier to keep your phone secure and minimize 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 & hold the Power button, then touch Power off.
Touch Lockdown.
Your fingerprint sensor and automatic unlock settings are disabled and notifications won’t be displayed on your lock screen.