Actually:
Invalid Attachment Meta does not provide a way to delete files directly. My goal was to first repair or delete the meta data. And afterwards (second index run) delete the files.
I am building a bulk delete meta/repair meta as we speak. I really need your json log file to check the possibilities. Also are you sure to delete the meta (and files) instead of repair? After repair you are still able to bulk delete images through the media library of wordpress.
Invalid Attachment Meta means: File Exists, Meta Exists, only the meta dimensions are incorrect. The plugin can easily repair the meta data in your database by replacing the incorrect dimensions with the real dimensions from the file.
I would love to debug your wordpress distribution to see if I can help out.