A user or a group is assigned a single vCenter Server role.
What happens if the role is removed?
Users or groups retain the permissions associated with the removed role until they are manually assigned a new role.
A role assigned to existing users or groups cannot be removed until all users or groups are removed from the role.
Users or groups are automatically assigned the Read Only role until an administrator can manually assign a new role.
Users or groups assigned the removed role no longer have any permissions in vCenter Server.