I can just uninstall the program, delete the library and reinstall and rebuild. But thought I'd pass it along in case it comes up again.
Don't do that. It is very unlikely to fix the problem. As Spike says, the image of your Credit Card number is probably embedded in the audio file itself, so reinstalling and reimporting will just put it back into MC. Didn't Apple use to put CC data into purchased audio files at one stage, as an image, as part of its DRM?
Anyway, you could try what Spike suggested. Also if you looked in the Cover Art and Audio file locations and didn't find an image, based on the images you posted the CC image is in the Thumbnail database, probably from an earlier time. Just rebuilding Thumbnails may get rid of it.
PS: A search for "*.jpg *.png" would cover all formats MC uses for Cover Art. But I don't think you will find the image on disk. It will be inside the files or only in the Thumbnail database.