Deleting a user from the Manager Menu | Administration | ZENworks Asset Management Users seems to remove the user, but the user can still login and is still there when going back into the ZENworks Asset Management Users section.
Fixed in ZENworks Asset Management 7.5 Interim Release 22 or newer
Interim Releases can be scheduled to run automatically or can be downloaded manually at https://download.novell.com/patch/finder. The Interim releases can be set up within the ZAM Manager for the Task server to check the site on a scheduled basis, and download and apply them automatically. Please refer to the Help Section details of how to set up automatic downloads if desired.
Each interim release is cumulative. If Interim Release 22 is not available due to a newer interim release being placed on the website, be assured that the code needed is in the later release.