The calendar you requested could not be found. Please make sure you are logged in to the correct account and have not deleted the calendar."

When I click on the link "Stop Getting Notifications", I get "

Outlook Calendar has new and improved reminders

We've listened to your feedback and know you'd like better reminders with more flexibility. So, now you can:

• Set up multiple reminders for each event and send them to your email address.
• Set up different reminders for each one of your calendars. New events that you create on each calendar will get those reminders by default. (Don't worry, you can still set different reminders for individual events.)
• Get notified when someone updates an event or task on a shared calendar.

To get started, click Start using new reminders, then set them up the way you want them. Once you've clicked it, we'll also save any changes you've made on this page. Note: In the next few months, all Calendar users will automatically start using new reminders. So, once you click Start using new reminders, you can't go back to the old reminders."

I think that Microsoft has a back up somewhere from an old calendar and the sync didn't happen when I deleted that calendar. 

How do I stop reminders?