Desinstale o Windows Update KB3035583 e reinicie o computador.
Esta não é a minha própria resposta, pois obtive isso da transcrição do Security Now, disponível em grc.com. Sua resposta é:
So that's the path in the registry, HKLM\Software\Policies\Microsoft\Windows\GWX. Under this GWX key you create a DWORD value named Disable, with capital D, lowercase "isable," so Disable, all caps GWX, and give that the value of one, and you are done. You have disabled Get Windows 10. And whatever Microsoft chooses to do, apparently they will honor that. It works today. We can hope it continues working.
Fonte: link
Espero que isso ajude.