i'm not sure why you wouldn't just sync your device and select the tracks and delete. sync your phone/ipod select the music tab under that device. highlight tracks to be removed then right click and choose delete.
i found this by typing "remove music" in the help section of itunes. if that doesn't help then i'm sure an Apple phone rep would be glad to talk you thru it.
http://support.apple.com/kb/index?p....html&answerid=16777218&src=support_site.home