Hola Alex y gracias por usar los foros de TechNet, esta notificación no se puede desactivar, pero puedes ignorarla si no deseas actualizar, aparecerá una vez a la semana durante el primer mes y dos veces al mes en adelante
Why am I seeing a "Get Windows 8.1 for free" notification?
If you're running Windows 8, you'll likely see a periodic notification to update to
Windows 8.1. The first time you receive the update notification, you'll have the option to go to the Windows Store where you can begin the process of updating to
Windows 8.1. If you dismiss the notification, you'll receive reminders once a week for the first month, and then twice per month until you update.
Saludos.
