Locate your downloads folder:
First, you need to navigate to your downloads folder. This is located at: C:\Windows\SoftwareDistribution\Download
Here you will find any Windows updates that have been downloaded, but not installed. Delete any updates you want, or delete them all.
Receive an Error?
If you received an error, it may be because the Windows update service is still running. Hit your Windows key, and type in services.msc
The service you are looking to stop is called Automatic Update Service. Double click it, and select Stop.