An error occurred while saving the commentMartinT commented
This looks to have been addressed. If you find the meeting in your chat history, you will see the view and add participants button in the top right hand corner with a count of participants. Clicking this will give you a popup menu with a list of people, that have been in the meeting. Click the x next to the person you wish to remove. A warning message identifies that they will see the chat history (but presumably not new messages).
I have not found a way to do this through the calendar for recurring meetings only chat history.