In Altiris 7.5 HF5 and below deleting images that are no longer needed is a three step process and is very cujmbersome and also varies based on the type of image you are deleting. Deploy Image:. Settings/All Settings/Deployment and Migration/Disk Images - delete deploy image not needed. Then manage All Resorces/Default/All Resources/Software Component/Image Resource - select images not needed. Then go to each site server and find the guid for images not needed.
Seems there should be a Menu or single point to delete images that are no longer needed and doesn't take so much time and effort to manage them.
Just an idea.
Ken