If you have the same user enrolled in several courses, simply use the following fields
username - firstname - lastname - suspended - enrolstatus1 - course1 - enrolstatus2 - course2
And you can even mark "0" for one course and "1" for another course.
You can leave the student active on the site and inactive in some or all courses. He will then be able to log in, but will not be able to access the courses.
Anyway, from the combination of "suspended" and "enrolstatus1" can do anything with the student's registration.