Windows 8 provides user’s with the option to turn off the notifications received from apps. Using this feature, users can disable notifications from all apps or from selected apps.
Click the Settings –> More PC Settings under Windows 8 sidebar
In the PC Settings screen, navigate to Notifications section
Users can completely disable notifications for all apps by setting the value as Off for Show app notifications. Users can also turn off notification based on individual app.
Like in the above example, notifications from Xbox Companion and Xbox Live Games have been disabled.