To disable any type of notification on Windows 10 for example Outlook's new follow the steps below:
1) Right click on your Start Menu button (bottom left corner of the screen) and select Settings.
2) In the Windows Settings in the Search text box, type in 'Notification' and select option Notifications & actions settings.
3) Scroll down to the toggle buttons next to Applications names and click on a toggle you want to switch off to stop receiving notifications.
One of the applications will be Outlook for example.
4) Once you turn off unwanted notifications for chosen apps, you can close the settings window.