Reducing disk space usage and images disappear. Woops!

I am the webmaster for a popular local blog that is up in the orange of its disk space usage. I thought a way to minimize the usage would be to remove all links from images in the blog and manually remove all the other versions of the images that Wordpress creates automatically.

When I did it, I checked each post, and the photo was there. When I check the post from the drop-own archive widget on the sidebar, there are no photos. Is that the way it is supposed to work?? Do the widgets leave out images?

thanks!