What is the proper way to disable former CRM users with the new Office 365 administration?

I need to remove a bunch of users that are no longer using CRM, but I don't want to remove what they worked on in CRM, i.e. cases, activities, custom entities, tracked emails, etc. Is there a proper way to do this?  It's silly to retain licenses for former users.  I found instructions on how to disable them in the old Dynamics managed interface, but not in the office 365 administration.  

Thanks!