Black Box where featured image used to be

After installing this plugin and editing a page with the featured image set, when I select remove featured image, the image is removed, but the space where the image was is now a big blank / black area. I was expecting the image and the area the image took up to be removed, not just the image removed and a blank space to remain. Is it possible to remove the space the image took up as well so just the post appears?

The page I need help with: [log in to see the link]