Remove a tentative meeting that's automatically added to your calendar
When you receive a meeting invitation, Microsoft Outlook automatically adds the meeting to your calendar as a tentative meeting. If you delete the invitation, the tentative meeting remains in your calendar, and Outlook adds the following entry to the Application log:
Source: "Outlook"
Event ID: "64"
Level: "Information"
Description: "A meeting request has been deleted but the meeting will remain tentative on the calendar
until the user either chooses a response or deletes the item directly from the calendar folder. Subject:
<meeting title> ..."
If you want to remove the tentative meeting from your calendar, or from the calendar of a mailbox for which you have delegate permissions, follow these steps:
Right-click the meeting in the calendar, and then select Decline or Delete.
Select any of the response options.