After upgrading to Windows 10 you may have noticed birthday reminders on your lock screen or desktop popping up for people you may not even remember. Because of integration with LinkedIn, other email services and social media sites anybody you have every had a connection with has a birthday notification. And if you know enough people everyday is somebody’s birthday, sometimes several somebodies. Personally, I only need to remember birthdays of my immediately family members. Everything else is just noise.
To correct this open the Windows 10 Calendar app. Either select All apps from the start menu and find it in the list or type Calendar in the search box.
With the Calendar app open, uncheck Birthday Calendar for all accounts that you have connected to Windows 10 apps.
This should disable any unwanted birthday notification associated with Windows 10 apps. If you have any third party apps that provides notifications, you will have to configure the settings in that app.