Hi Vijay,
I have come across this as well myself. If you add 'Enrolment Types' as a report column, you will likely see that this column is empty for the people who should have been un-enrolled.
With this logic, you can then add a report filter for 'Enrolment Types', and set it to 'Any of the selected', and select all Enrolment Types. This will exclude all of the employees that have no enrolment type, thus excluding the unenrolled employees.
I know it seems a bit convoluted, but I've unfortunately not found any other way to exclude them from reporting.
Hope that helps!