Is it your goal to delete events that are no longer attached to people and families?
There is the Remove Unused Objects tool. You can run it for all objects or just on specific areas.
If your goal is to identify unused events to then do something with them, you will need to create a custom filter. For unused events it will be in the Events list, and the filter will be…
General Filters >> Events with reference count of <count> Set the value to Equal to 0
One thing to remember when using the remove unused objects tool, A citation attached to an event will not show for possible deletion until the event is deleted. The same for a note attached to the citation. Sometimes it is necessary to run the tool a few times to delete nested objects.
I never delete no longer needed Places, Sources or Repositories. Someday I might and why recreate them.