You can delete the unwanted pictures when browsing the AlbumSaver. In the app, you should see a small folder icon, if you hover it will display "browse". Click on this icon and you're able to see the pictures that were transferred to the AlbumSaver. You're able to delete the pictures from there.
AlbumSaver software is using either Windows Explorer or Mac Finder for browsing the pictures and videos on your AlbumSaver.