MP3 attached…

For my very first post I debated if I wanted to include an MP3 of a song at the bottom of my post. I previewed it and such. In the end I decided not to. I was happy with my first post BUT when I did an RSS look of the post. The MP3 of the song was at the bottom next to comments. How do I delete it and what’s the deal with that?

Thank you —
??