Open a command prompt window and navigate to the folder using the cd command. you can use the * as a wildcard so you dont need to type the full dir name. once located use the del command to delete the file. remember you can use * as a wildcard, just make darn sure if you type del track*.mp3, trackname.mp3 had better come first alphabetically.
(And of coarse, by "trackname.mp3" i mean the file u want gone.)