Thank you for the thoughtful response to my question.
Unfortunately, the solution you suggested will not work in my case. My course is extremely short; I only meet with each group of students for one week. The course is an orientation-type course preparing these adult learners for remote learning experiences. After the week with me, they matriculate into their formal online courses.
With 15-30 students per week, the Discussion posts add up quickly, as do Assignment submissions.
It would help greatly if, when students are removed from my course, any work associated with their account would also be erased. Currently, the IT person cleans up my roll every 2 weeks. So, students are removed from the course, but all their work remains.