cannot delete files in podcasts

I have the latest version of Itunes on my win10 pc. I download mp3 files of old radio programs and add them to itunes. I then convert them to podcasts and they show up in my podcast directory. One such show, creates a directory of these fies. When I look at this directory it shows no files( played, saved or unplayed). Im synching to my old ipod 5th generation. The ipod shows these files and I can play them.

So I thought to get rid of them I would delete the directory, and a warning comes up to inform me that Im about to delete 58 files. When I delete them,I synch with the ipod assuming all those files are gone but they are not. I cant think of a way to get rid of these files, any suggestions?

Thanks