I noticed that once you have added a background music file, you cannot get rid of it without substituting another file. Yes, you can disable it. But it would be nice if you could either clear the entry or delete it.
I think he means inside the Page Editor->Music tab. Once you have a music file entered, you cannot get rid of it. You can enable/disable to control publishing the code, and you can select a new file, but you cannot delete or remove the current selection.