Here are a couple of ways you can try to remove the unwanted calendar in Outlook:
1. Close the Calendar Group:
- In Outlook, navigate to the calendar list on the left side of the window.
- Click the dropdown arrow next to "My Calendars."
- Find the unwanted calendar and right-click on it.
- Choose "Close Group" from the menu.
This should simply close the calendar group, effectively removing it from your view.
2. Use Account Settings (Even Though There's No Extra Account):
- Go to the "File" tab in Outlook.
- Click on "Info."
- Select "Account Settings" and then "Account Settings" again.
- In the window that appears, look for the unwanted calendar listed under "Data Files" or "Email Accounts" (depending on your Outlook version).
- Even if there's no separate email address associated with it, you might see the calendar listed there.
- Important: Do not remove any email accounts you actually use.
- If you see the unwanted calendar listed, try selecting it and clicking "Remove."
3. Try Outlook Web App:
- Log in to your Outlook account through a web browser using https://www.microsoft.com/en-us/microsoft-365/outlook/email-and-calendar-software-microsoft-outlook.
- In the web app, navigate to the calendar section.
- You might be able to remove the unwanted calendar directly from the web interface.