Plugin leave image on disk

Plugin create on disk additional files with images sizes (not registered sizes – this is wrong).
By default plugin create image 45×45 pixels – this is registered image size – this is correct.
If user set his own, specified thumb height and thumb width plugin create another file on server disk into upload folder.
This sizes are not registered!
If user delete image from media library, not every files are removed from disk.
Wordpress not remove files with not registered dimensions.
This plugin create files with not registered dimensions which are not removed from server.