Remove unwanted office 2010 & 2013 outlook calendars from my office 365 outlook.

Question

Cant delete old shared calendars in office 365.

I continually receive a popup window containing reminders about agenda items in a calendar.

It does not tell me which calendar contains these items and when I open the calendars I still own, both the MAPI and the shared calendars, I don't see any entries as if I have never entered any appointments, which is true because I don't use the PC version of calendars anymore for my appointments only my mobile office 365 outlook app.

But to my great displeasure I keep getting these reminders about very old appointments which I entered when I DID use the PC calendar and OFFICE 2010 & 2013 OUTLOOK PROGRAMS.

what do need to do to delete these old calendars?

Answer 1

Hi Rob,

Those reminders are often triggered by outdated Outlook profile data or cached calendar folders that were inherited from previous versions like Office 2010 or 2013. Even if the calendars are no longer visible in your current mailbox, the local Outlook profile may still contain cached reminders or old data files that cause these pop-ups.

A practical solution to this issue is to create a new Outlook profile. This process rebuilds the mailbox configuration from the server and eliminates any old local cache that might still hold those legacy calendar reminders.

Here’s how you can do it:

1. Close Outlook.
2. Open Control Panel → Mail → Show Profiles.
3. Click Add and create a new Outlook profile.
4. Add your Microsoft 365 account and set the new profile as the default.
5. Open Outlook again using the new profile.

If the reminders were originating from old cached calendar data, they should cease appearing because the new profile starts with a clean mailbox cache.

However, if the reminders persist after creating a new profile, you can take another step by clearing Outlook reminders. Open Outlook → Reminder window → Dismiss All, as sometimes old reminder items remain stored locally even after the calendar entries are deleted.

Answer 2

To stop the old reminders and remove the unwanted calendars in classic Outlook for Windows, use these steps in order.

1. Remove or delete the old calendars

If the old calendars are still visible under Calendar:

1. Go to Calendar in Outlook.
2. In the Folder Pane, locate each old or shared calendar.
3. For calendars that are no longer needed:
   1. Right‑click the calendar name.
   2. Select Delete Calendar (or Delete Group for a calendar group).
   3. Select Yes to confirm.

This removes the calendar from the folder pane. For shared/team/SharePoint calendars, only the local copy is removed; the source calendar remains intact.

If the Delete command is greyed out, that calendar is likely the primary calendar and cannot be deleted. In that case, skip to the next section to clear items instead.

2. Clear all items from the primary calendar (if reminders are coming from there)

If reminders are coming from the primary calendar and it cannot be deleted, clear all items:

1. In Calendar, select the primary calendar.
2. On the ribbon, select View.
3. In Current View, select Change View > List.
4. Click in the item list and press Ctrl+A to select all items.
5. Right‑click the selected items and choose Delete.

This permanently deletes all calendar items (including old holidays and appointments) from the primary calendar.

3. Remove shared, team, group, and SharePoint calendars

If the reminders are from shared or legacy calendars that still appear under your calendars:

1. In Calendar, in the Folder Pane, right‑click the shared/team/group/SharePoint calendar.
2. Select Delete Calendar or Delete Group.
3. Confirm with Yes.

Only the copy in the profile is removed; the source calendar remains for the owner.

4. If reminders still appear after cleanup

If reminders continue after deleting/clearing calendars, there may be corrupted reminder entries. In that case, use the MFCMAPI method to remove corrupted reminders:

1. Empty the Deleted Items folder in Outlook.
2. Put Outlook Work Offline (Send/Receive tab > Work Offline) and close Outlook.
3. Download and run MFCMAPI.
4. In MFCMAPI, use Session > Logon and Display Store Table and open the mailbox store.
5. Expand Root – Mailbox > Finder, then double‑click Reminders.
6. Locate the old recurring appointments by Subject or To.
7. Right‑click each unwanted reminder and select Delete Message.
8. In the Delete Item dialog, choose a permanent deletion option and click OK.
9. Run outlook.exe /cleanreminders to clean the reminder cache and start Outlook.

Use MFCMAPI carefully; incorrect changes can permanently damage mailbox data.

After these steps, the old calendars and their reminders should no longer appear in Outlook on the PC, and only current calendars (such as those used by the mobile Outlook app) will generate reminders.

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References:

• Delete a calendar in Outlook
• You can't remove a calendar item or an email message in Outlook in Microsoft 365
• How to enable and disable the Outlook calendar sharing updates