You can use an audio editor. A free one which can open mp3's, etc. is this one Audacity (click on link). What I'd recommend is converting the song to WAV. Then do your editing. Keep a backup of each step of editing in case of errors. Then after you're finished, resave as mp3 or whatever format your phone is capable of importing.

BTW the program comes with separate downlds. The manual is separate & the plug-in enabler is separate. So be aware of that.