Hello jaytee 28 -
Without the actual names, which is what it sounds like you refer to with "$_57.jpg", it is difficult to locate specific images in your image management area. However, when you are deleting Saved Listings there is an option to also "Delete Associated Images" which will delete the images from that listing when you delete the saved listing. Please note that this option does not occur from the Closed Listings page of your account as if you delete there, it only deletes the record of the closed listing, not the actual saved listing in your account. If you go into Saved and delete the listing from there, you will have the option to also remove the images associated with that listing.
Please note, however, that if you delete the images from your account that are in a particular saved listing, this deletes the image entirely - so if you use an image in more than one location, the image will no longer be available elsewhere.