Hello Yang,
Changing Cohort/Sync Student to a Manual enrollment for Suspension using 2.2:
1. Do Not remove the User from the existing Cohort.
2. First, manually enroll the User as an individual User into ALL of the Courses in which her/his site-wide Cohort is currently sync'ed. You can manually enroll the existing User through each of the respective Courses (Course Administration> Users> Enrolled users). You'll notice that the Enrolled User's line within the Course will now display Manual enrollments in addition to the Cohort sync status.
3. Then, and only then, can you remove the User from the old Cohort without effecting that User's accumulated data that had been stored when the User was a part of the old, site-wide Cohort. Again, do this only after manually enrolling the User into All of the Courses in which the original Cohort sync was enrolled.
4. Notice that, within the Course, the old Cohort sync status no longer displays on that particular Enrolled User's line. You can, then, suspend the User through the now visible, Manual enrollments link within one or more of the applicable courses.
Strong Recommendation: Test this, first, by creating a fictitious User. Enroll that User into an existing site-wide Cohort (via Site Administration>User>Account>Cohorts>Edit users). Confirm that the User is appearing in All of the Courses that the existing cohort is enrolled.
Log-out and log-in again as the fictitious User, and submit various course elements of your choosing, like quizzes, etc. You can then confirm as the Admin/Teacher/..., that these submissions have been registered in the Grade Book.
Go through the above steps of changing the status of a Cohort/Sync Student to a Manual enrollment and confirm that there was no loss of the fictitious User's previously existing data.
Hopefully, there aren't too many Users in need of suspension; this workaround can be a tedious endeavor when multiple Users are enrolled in Courses through multiple Cohorts.