Edit Jan 12 2017: Added clarification about rebooting.
Updates in this day and age are more important than ever: they squash all those small bugs that make the computer misbehave, make your computer more secure, and add additional functionality that wasn’t previously available. There are, however, cases where you may want to disable them because an update breaks something or introduces a software regression, causing your applications not to work as intended. Here’s how to disable Windows Update.
To be completely clear, if your computer works as intended with updates, I strongly suggest you do not follow this guide and keep installing updates as usual. I’m not responsible if you get viruses that open porn at random. But then again, you may actually enjoy them opening on their own, so… Yeah. I am aware that there are a few utilities that do exactly that, but if your operating system already has a way to do it without installing third party (and potentially malicious) software, all the better.
Open the Services applet
The Services applet is a tool that allows you to manage all services running on your computer, provided that you have an account with administration rights. To open it, click the Start button and scroll all the way to the bottom until you find the Windows Administrative Services folder. Open it and click Settings.
You’ll be presented with a list of all the services available on your computer. Don’t be scared by their sheer number: they don’t bite (at least not usually) and we only need to edit one entry. Scroll all the way down to the entry named Windows Update.
The default value of the Startup type column is Manual (Trigger Start). We want to change this to Disabled. To do this, double-click the entry or right-click it and select Properties. In the middle of the popup window is a drop-down box marked Startup type. Change its value to Disabled and click OK.
Close the Services applet.
Check if the Windows Update service is still running
In order to make sure that the service isn’t running anymore, open the Command Prompt and type in the command
SC QUERY WUAUSERV
Look up the STATE row. If it’s followed by STOPPED, everything worked as expected.
You may need to reboot your computer for the change to take effect.