Have you checked in the "Smart Lock" option in "Security&Location" settings. It would be labeled as "Trusted Face". Please check once.
@mehtasameer2087: Not sure if you have tried setting up Trusted Face and then tried to unlock the device just by face recognition (no need for pin or fingerprint).
On my device, it works exactly as expected. When the trusted face (actually multiple faces) is configured, the device unlocks without needing anything else. In fact, if one looks closely towards the bottom of the lock screen when Trusted Face recognition is successful, one would see a 'unlocked lock' icon appear exactly where the fingerprint icon was being shown. The problem is that after a successful face unlock, the lock screen doesn't automatically disappear, even though the phone has been unlocked and the 'unlocked lock' icon is visible. One still needs to swipe up to dismiss the lock screen and that may be causing the confusion for some users. That said, Trusted Face is the mechanism to do Face Unlock and is working as expected. Please try it out again observe that 'unlocked' icon.