Steps to reproduce:
1. Schedule a capture, checking "add live event to opencast media module"
2. Before the capture starts, try to delete the event
Dialog shows that the event needs to be retracted, but there's no operation to retract from the 'live' channel.
Workaround (if any):
The LIve Scheduler service listens to messages from services, including delete messages, to update/retract the live media package from the search index, but the admin UI blocks the deletion if the event has a publication channel.