In the Project Panel (where all media Imported into the Project is shown), Delete the files there first.
Get into the project.prel with the missing media by clicking Skip All on the Missing Media messages that you encounter trying to open the project.
Then delete all instances for the missing file or files in all of the following locations:
b. Organize Header Media Tab in row below the Organize
c. Organize Header, Project Tab in row below the Organize Header
The files that you seek should have the characteristic red green arrows which form a circle look.
Bingo, ATR! Your solution was perfect. Under Organizer, the Project choice showed used, unused, and offline files. Selecting and deleting those achieved exactly what I was attempting to do. Premiere 9 no longer asks for unused files, which I have now sent to cyberspace.