If you are in Sitebuilder Plus, click on the site/domain name in the top right corner. You will see "View File Manager". Click that and delete any files you don't need. You can change "Browse By" at the top to "Thumbnail" to see the images easier.
Thank you, that is what I needed. The location for "File Manager" isn't intuitive. When I am working on my "Gallery", why would I look on a separate page for the source of my pictures and documents? Also, if I am editing the pictures that appear on the page, why can't I Right-click to remove them?