by Ken Task.
Don't think there is an option in course backup preferences to select only student role removal - keeping all other roles in the course.
Restoring backups to new instance would also mean mega work in putting those backups in their proper category.
Path of least resistance might be to:
1. clone the current site - upgrade if needed via git.
2. once new site is responding to new FQDN - search and replace performed -
use command line moosh to reset all courses - removing role ID 5 (student)
from all the courses. Looping bash shell script that loops through all the course
ID's.
Student accounts are still present in new server.
Before you do that, however, set recyclebin to least amount of time to retain.
'SoS', Ken