For any reason pertaining to your company, certain users can be suspended / un-suspended from the Manage users window. Their names will be displayed in red during the suspension period.
While they are suspended, users will not have access to the YArooms platform. After they are un-suspended access will be available again and they will find all their meetings untouched (unless an administrator chose to expressly edit/cancel them).
Note: The total number of registered users (including users who are currently suspended) cannot exceed the maximum user limit of the billing plan you are on. Deleted users do not go towards this total count and neither do users who access the platform through the Guest user button.