Worst scenario: You're almost done with work you've been laboring over when Windows starts with the popups to restart your computer, OR, even worse: You had to leave for a minute and return and find that Windows has restarted your computer and your work? Gone. Hell, even Adobe Photoshop and Lightroom save your work at configurable intervals (via Preferences). So why don't the Window and third party apps? Because.

Anyway, MakeUseOf  has put out a great article on how to edit your registry (make a backup first!) and Group policy to prevent having to reboot when MS tells you to, and even how to implement the registry change without a reboot. After all, that was kinda the point, right?

So this hack works on all versions of Windows all the way back to XP. 

Screenshots help a lot, so I advise looking at the linked article here: http://www.makeuseof.com/tag/disable-forced-restarts-windows-update/ 

There's also no reason to repeat everything already there, 

Just remember: Make a registry backup before editing, and create a "Restore point", just in case.

Here's a "How to" make a registry backup: http://www.howtogeek.com/197785/how-to-backup-and-restore-the-windows-registry/ : Use the System Restore to backup your registry.

On W8 and W10, here's how to boot to safe mode the easy way: http://www.howtogeek.com/107511/how-to-boot-into-safe-mode-on-windows-8-the-easy-way/

Source:

http://www.makeuseof.com/tag/disable-forced-restarts-windows-update/