For some reason, Co-organizers are able to delete sessions. I scheduled several sessions for a national audience and then published the registration links. I included one of my colleagues as a co-organizer on the sessions. Several weeks later, she deleted one of the sessions, not recalling that I made her a co-organizer and not understanding why she had multiple events in the same day.
A Co-organizer should not be able to delete any event. This seems like an oversight to me. This should be part of the hierarchy of permissions. The co-organizer shouldn't be able to change the date/times of the session, nor should they be able to cancel. The scheduling organizer should be the only one who can change or delete.