We've all been there: You go to shut down your machine, but you see that dreaded Windows Update icon that means your computer might stay powered on, installing updates for the next 20 minutes. If you want to shut it down immediately, you can trick it by going to the lock screen first.
To avoid installing updates when you shut down, all you need to do is lock your computer (which you can do by pressing Win+L). Then, from that screen, head down to the shut down button, where you'll see an option to "Install Updates and Shut Down" or just "Shut Down" -- an option you don't get from the regular ol' Start menu.
Choose "Shut Down" and you can wait to install those updates when you aren't in a rush. For a more permanent solution, of course, you can hack the registry, but this will do in a pinch (and you should be installing updates when you can).