Can I change a user to a non user?  Two examples of reasons I want / need to do this:

1. I have staff members who have moved departments. They no longer use a computer so will no longer be a user, but a non-user. They do however need to stay on the system.

2. I have a a group of people who have left the company who were users and are no longer here. Am I able to 'deactivate' them and use the licences for their replacements?