You can lock your PC if you aren't using it but don't want to sign out. Once you've locked your PC, or if your PC has gone to sleep after a period of inactivity, you need to dismiss the lock screen to use it again.
Open Start by swiping in from the right edge of the screen (or if you're using a mouse, pointing to the upper-right corner of the screen and moving the mouse pointer down), and then tapping or clicking Start.
Tap or click your account picture in the upper-right corner, and then choose Lock.
Swipe up from the bottom edge of the screen (or press any key if you're using a keyboard) to dismiss the lock screen.
In the sign-in screen, sign in to your PC using the method of your choice.
If you have multiple user accounts on your PC and you want to sign in with a different one, tap or click the Back button and choose an account. If you're prompted to press Ctrl+Alt+Delete, do so.
To pick a different sign-in method, tap or click Sign-in options to see the available choices.