Welcome to the Centrify forums.
Keep in mind that user accounts don't exist in the local UNIX/Linux/Mac Centrified system. They exist in Active Directory.
All you need to do to get rid of traces of a previous user is remove their home directory. Most of the time you can do a sudo rm -rf /home/[username] and get rid of the data, however in enterprise environments most of the time these are backed up and reviewed just in case there is critical data (e.g. same in Windows or when deleting Exchange inboxes).
Let us know if this helps.
R.P