Microsoft’s popup reminder about Windows 10 is an aggressive marketing campaign that has the signs of a malware infection, and while the get Windows 10 message is not a virus it is certainly annoying.
Remove a Windows Update, Kill the Upgrade Notification
The notification came via a Windows Update, so why not remove the update?
Uninstalling a Windows Update is surprisingly easy, as long as you know its name. This update is called KB3035583 so we can use the command line to delete it with a single command. Begin by opening the Command Prompt with Administrator privileges (right-click the Command Prompt icon and select Run as administrator) and enter
WUSA /UNINSTALL /KB:3035583
Follow the on-screen prompts, and when complete type exit to close Command Prompt.