Looks like Windows 10 Update auto-restarts your PC whenever it wants even if you disable the automatic updates it still does what it wants.
Here is a fix for this problem, how to stop Windows 10 Update to Auto-Restart your PC for real.
- Type this in Windows search
- Hit enter and open the UpdateOrchestrator folder.
- Right-Click with your mouse on the Reboot file and select Rename to rename it to Reboot.old or whatever you like.
4. Create a new folder called Reboot
Now Windows 10 will not be able to auto restart you computer when you leave it on over night or when you are away from your computer.
Update: Microsoft added two new files which needs to be replaced with a folder: Reboot_AC and Reboot_Battery