The HiLO Lens app stores images and video on the main Camera Roll. There is not a private HiLO Lens media library. This makes some things easier (e.g. syncing photos with a computer) but has some limitations. The iOS system does not allow an app to delete images from the Camera Roll so to do this you can use the default Apple Photos app. Sorry for the inconvenience and we hope Apple will lift this limitation in the future!