If you are using the Administrator program to edit or create users in Infor CRM software, you will notice one of the attributes you can set is User Type. User Type determines what sort of license is consumed by that user. You may notice one of the the available User Types is Retired User. This user type is very important, because under normal circumstances, it is very bad to delete a user. If a user no longer needs access to CRM, Infor CRM best practice is to switch the User Type to Retired User. That user will no longer be able to log in to CRM, and any license they were using will be freed up. The user will still exist in the database, so they will still show up in records. If a user is instead deleted from Infor CRM, any references to that user will now refer to nothing, and trying to bring up records with references to a deleted user will frequently result in the system throwing an error.
So, to reiterate, when a user leaves the company, or otherwise no longer needs access to Infor CRM software; do not delete that user, move them to Retired User status. This disables their login, frees up any user license, and leaves the database intact.