by Ken Task.
And a follow up question ...
What version of Moodle? Kinda important as the GUI admin in higher version 4's have placed course backup/reuse in a totally background process with no button to cancel or 'undo'. If that background process fails one has some work to do to clean up.
Also ... some references to docs .. which I think applies to this thread as well as your other related thread:
https://docs.moodle.org/405/en/Unenrolment
https://docs.moodle.org/405/en/course/delete
'SoS', Ken