There's WAY more to this issue than claimed in this article
I've made some tools to help put an end to this coerced Windows 10 installation nonsense. They can be downloaded from here:
The three included tools uninstall the Windows 10 nagware and the Microsoft "telemetry" (spyware) "updates" from Windows 7 and Windows 8.x Operating Systems if they are installed, prevent the updates from being reinstalled, and remove the Windows 10 installer folder $WINDOWS.~BT if it is present.
These tools must be run from an account with Administrative privilege, which is the case (unfortunately) for most accounts. They can also be run from a non-Administrator account by right-clicking them and then left-clicking on "Run as Administrator".
The tools are most effective when run in the following order:
1. Run PreventW10InstallationUAC.exe to set Microsoft Update to "manual only" mode and modify a couple of registry variables that tell the OS to never allow a newer OS to be installed. This tool will run quickly unless you accept the optional request (recommended) to make a System Restore Point before the tool makes it changes, in which case the Restore Point will take a while to make.
Note that after this procedure finishes, no more Microsoft updates will be applied unless you manually request a check for updates and then decide which updates to accept, though making such decisions requires knowledge that the average user usually does not possess. However, for mature operating systems I personally believe that blindly accepting Microsoft updates at this juncture has more downsides than upsides.
(If you DO want to attempt to manually check for updates, you'll first have to change the Windows Update setting from "Never Check for Updates" to "Check for updates but let me choose whether to download and install them" before you click the "Check for updates" button.)
2. Run RemoveW10NagwareTool.exe to remove a set of Microsoft updates that relate to Windows 10 nagware ("white flag") popup, Microsoft spyware, and the Windows 10 installer itself if any of them have been installed. Detection and uninstallation can take a few minutes to complete.
If any of this set of updates is found, you'll need to reboot the system.
It might also be necessary to run this tool again after rebooting if the nagware update had previously been slated to be installed AGAIN, in which case after rebooting, you'll STILL see the Windows 10 ("white flag") nag. If that's the case, just run this tool again and reboot again, and then run PreventW10InstallationUAC.exe again.
3. Finally, after you're sure the Windows 10 nagware has been removed, run RemoveW10Folder.exe to detect and remove the Windows 10 install folder if it is found.