Two registry edits are all that is needed to prevent the W10 unwanted update.
Steve Gibson - GRC.com
https://www.grc.com/never10.htm
Never10 manipulates the values and security permission settings of the following two registry keys:- HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\Gwx
Under this key, the 32-bit DWORD value “DisableGwx” is set to 1 or completely deleted.
These will be referred to as the “Gwx” key and the “DisableGwx” value. This key and value control the display of the “Get Windows 10” offer icon in the system tray. When DisableGwx is set to 1, the upgrade offer icon is suppressed.
- HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\Windo wsUpdate
Under this key, the 32-bit DWORD value “DisableOSUpgrade” is set to 1 or completely deleted.
These will be referred to as the “WindowsUpdate” key and the “DisableOSUpgrade” value. This key and value control the downloading and installation of any upgrades to Windows. When DisableOSUpgrade is set to 1, any previously downloaded Windows 10 files are deleted and Windows will never attempt to upgrade the current operating system.