Registry hack method from the Register
GUI tools
Destroy Windows 10 Spying http://dws.wzor.net/
Running this on a 7/8/8.1 system will give you the option to remove the GWX feature.
If you just simply want to disable gwx without the options to remove telemetry and/or patches you can use GWX Control Panel to either temporarily or permanently remove it. http://blog.ultimateoutsider.com/2015/08/using-gwx-stopper-to-permanently-remove.html
http://www.majorgeeks.com/files/details/gwx_control_panel.html