Assuming you didn't change the setting. It's turned on "Automatic" by default. Even if you turned it off (disabled), it's still physically "on", because it runs as a Windows Service, and eats up CPU cycles and memory resources better suited for things you truly need to use, even though it's not physically being used.
However, you can change the time or frequency of scheduled updates to best suit your needs.
Since your update was forced, as you said, that to me suggests your Automatic Update feature is enabled, and it's your fault, not your computer's, mine or Microsoft's fault that you leave it turned on.
Lastly, if your System Restore is disabled and you run into problems, don't come crying to me or Microsoft or post some stupid vanity here at FR about it.
I don't have this problem because I've set mine differently. My posts have been about 90+% of the people out there who haven't.
If Microsoft says the updates are automatically downloaded AND INSTALLED, then that is without intervention. How many people do you think are up at the default time of 3 AM to have the opportunity to watch the complete process and possibly cancel it? Basically none are, yet Microsoft states the process completes then. How is that? Because the install process is not prompted with the default settings.
What don't you understand about unattended installs? They start and finish without your involvement. That's also why an earlier poster stated he had to address this issue on his network. Do you think his users are prompted for his installs? No. Unattended upgrades are just that, unattended. This is what we IT guys try to do, so that users don't need to be educated or involved. It's all pretty simple.
You can disable the service.