I saw this question:
Dear Rondee support staff,
Quick question: When inviting users for a Scheduled Rondee Conference Call, is it possible to revoke a specific user access to the conference call after this user has received the RSVP email and been given an access code to the call?
I am sorry, it is not possible to do that. A user in the situation cannot be revoked. The only other solution you might want to consider would be to cancel the conference call entirely.