Users who login Windows 8.1 with their Microsoft account might have observed a reminder being displayed on the Start screen about their friend’s birthday. If you feel your memory is in good state and you do not require such reminders from windows simply, disable the reminder. Here’s a simple way to do it.
  • From Start screen, click on the Calendar app.
  • Within the app, slide your mouse cursor to the top right corner of the screen to open the Charm bar.
  • Click Settings > Options.
  • There is a “Birthday calendar” section in the Calendar settings.
  • Slide the bar from Show to Hide.