I was messing about and cloned a calendar event weekly through 2020 - only to discover that I could not delete the batch.  I had to individually delete each calendar event separately (250 of them!) - and to make matters worse, it takes 4 (four..count them...4!) clicks to delete each.  Delete, Confirm, and then you land on the master website list and have to navigate back to the calendar subpages before you delete the next one. 

Please consider allowing batch deleting - or allowing changes to a master cloned item to trickle down to its clones.