Three ways to lock Windows 10 when you are not using it.

1. 3 Ways to Lock Windows 10
Computer

2. Way 1: Open Start Menu, click the user icon and choose Lock in
the list.

3. Way 2: Press Ctrl, Alt and Del at the same time, and then
select Lock from the options.

4. Way 3: We divide this way into 2 steps.
Step 1: Type lock computer in the search box on taskbar and
choose Lock the computer when I leave it alone for a period of time.

5. Step 2: In the Screen Saver Settings dialog, choose On resume,
display logon screen and hit OK.