Stop Windows 10 Auto-Upgrade
Prevent automatic upgrade from Windows 7 or Windows 8x to Windows 10

Download the GWX Control Panel - Ultimate Outsider - Software Downloads (freeware 3rd party app)

Click on -
"Disable Get Windows 10 App (permanently remove icon)"
"Disable Operating System Upgrades in Windows Update"

The Windows 10 icon in the notification area (bottom-right of screen) should now be gone.

Additional Information from Microsoft
How to Stop Windows 7 or 8 from Downloading Windows 10 Automatically