I have a function that sideloads a YouTube thumbnail onto a page... but I want to remove the featured thumb on the page first (and remove all the various auto-generated sizes, too).
I'm assuming I want to use
delete_post_thumbnail() followed by
wp_delete_attachment() to un-associated the thumb from the post, and then kill the thumb file. Is that correct? And Will that also delete all the various thumb media files (the extra auto-generated sizes) from the disk?