The only way to remove an event from a multi-level event is to delete it if there is no revenue.

To delete the event:
  1. Go to Events > Search for your Multi-level event
  2. On the events tab of your multi-level event, select the individual event you want to delete and hit the dropdown arrow next to it
  3. Select Delete

NOTE: You may also mark the individual event as inactive, but this will not remove it from the event.