There are multiple ways to lock your PC when you leave its vicinity.
- Windows-L
Hit the Windows key and the L key on your keyboard. Keyboard shortcut for the lock.
2. Ctrl-Alt-Del
Press Ctrl-Alt-Delete. On the menu that pops up, click Lock.
3. Start button
Tap or click the Start button in the bottom-left corner. Click your user icon and then select Lock.
4. Auto lock via screen saver
Go to Control Panel > Appearance & Personalization > Change screen saver and then check the box for On resume, display logon screen.