I wish I'd noticed this earlier in the day, but it may be worth looking at GWX Control Panel (http://blog.ultimateoutsider.com/2015/08/using-gwx-stopper-to-perm

I wish I'd noticed this earlier in the day, but it may be worth looking at GWX Control Panel (http://blog.ultimateoutsider.com/2015/08/using-gwx-stopper-to-permanently-remove.html http://blog.ultimateoutsider.com/2015/08/using-gwx-stopper-t...) which provides simple steps to temporarily or permanently remove the (current) "Get Windows 10" system tray icon along with making the Registry changes to block upgrades from happening in Windows Update. It'll also let you easily remove the downloaded 5-6GB of Windows 10 upgrade files if they're already on the system.