Should the Learner accounts be unenrolled from their courses before an Admin deletes their accounts?

You can delete the user directly or unenroll and then delete it. If you delete the user before unenrolling, you can see that user as ‘inactive’ under the course as below:

The enrollments number will show active users + deleted in Preview as a learner page as shown below:

However, after deleting the user, you can also unenroll that user from course. We can see the unenrolled users under the ‘unenrolled tab’ as below: