I have some audiobook files with very annoying music on the background. is there any way to get rid of the music?
Only if the music was on a separate channel from the voice. You have to open the audio file in the likes of Audacity and examine it. http://www.videohelp.com/tools/Audacity
You can clean up hiss and some other white noise but unless it is on a separate track you can't get rid of background music or talking. If you did the recording and still have the book record it on Audacity through the sound card. That is what I do even though I own a license for all my books. That way I am not screwed if I lose the DRM or a dozen other ways your audio stops playing.