In the left-hand panel, click on Notifications and actions. Option 2: Slide the toggle next to Show notifications in the Action Center.Option 1: Choose the account you want to disable notifications on in the dropdown menu at the top of the screen, then mark the checkbox next to Show a notification banner.In the lower left-hand corner of the window, click on the Settings icon. To turn off mail notifications in Windows 10, just follow the simple step-by-step instructions below.