Since Windows 10, Microsoft has caught onto this and added a new service that checks if you disabled the Windows Update service and re-enables it automatically, and sets permissions that initially deny you from tampering with it that then makes this a little more challenging to get around, but still possible to do manually. I later found Windows Update Blocker (WUB) which does all of this for you in one click. I have been using it ever since, and have never again been nagged by any update or experienced an unexpected reboot: https://www.sordum.org/9470/windows-update-blocker-v1-5/