Deleting Imported media in iMovie
I imported files into iMovie, but even after making smaller files, so my movie isn't so larger, it seems that iMovie keeps using the older files, so I can't seem to make a small size movie. How can delete the older large files, so iMovie recognizes the smaller files that I am trying to import? If it involves deleting projects that use this media, I am fine with that. I am just trying to make a file that is smaller that approximately 4GBs. Any help would be welcomes, since I have looked around an can find nothing that will help me delete the import media/photos.
Thank you
iMac 27", macOS 10.13