Unlink vs. deactivate, unlink, delete

I received an email that I must 'unassign' one of my remaining 2 users in order to downgrade my plan. When I go to the User Management page as instructed (https://zoom.us/account/user#/), I find I can Deactivate, Unlink or Delete. Which of these steps is equivalent to 'unassign'? Or, where should I be looking for Unassign?