Totally agree about the new v. old comment. They "dummed down" the editor quite a bit in many areas.
Go into your image library and you'll see a way to delete your images.
TIP:As far as images go, I suggest you use folders for sorting.
The system they have is very weak for file management once you start collecting a large number of files that you wish to delete from time to time.
Something also missing is the ability to determine if an image is used in an existing email.
If you delete the image it will no longer be available in the email at large.