When removing an image in an article and replacing it with another one, this unlinks the article from the image in the Editor Uploads ('Used In' column) and links the new one. This is great, but what would be even better is that if you deleted an image from an article that a check is run. If that article is not being used in any other articles, it could ask you if you also want to remove it from your Files Manager as well. This would keep your Files Manager up to date and not have lots of old images in there that you don't need. Or... another idea is to do this but perhaps on publishing an article it does this check and then prompts you....