Most of us here, that have at least SOME expertise in dealing with MS Windows, can handle things like editing the registry, etc., but...
there are many who read these forums looking for help, advise, inspiration, but have little to zero PC/Windows expertise.
I recently tackled this thread's topic, from the standpoint of the complete amateur.
Like has been said many times, "there's more than one way to skin a cat" or, to disable the 'Get Windows Ten' offer and System tray icon.
I really wanted to just delete all the files inside the GWX folder, but due to their highly protected status, that wasn't happening.
I did find out though, that I could effectively disable them from loading and running by just renaming the folder itself.
That's something I COULD do, and it's easily reversible, if I ever want to get the Windows Ten upgrade, in the future.
I just located the GWX folder, (C:\Windows\System32\GWX) right clicked on GWX and clicked Rename and added "old" to the end of the name, making it "GWXold" and hit ENTER and the job was done. On reboot, the little white Windows 10 icon was gone from the system tray.
I did that on two laptops and one desktop PC, running Windows 8.1 and the result was the same on every PC, so I'm hoping it will work as well on other PC's.
If anyone is willing to try my fix, I'd love to hear some feedback, either here or by PM.
Cheers Mates!
TechnoMage