I had this problem too and I figured it out just now. If your songs won't delete, go to settings, then General, then Usage, and it will give you a list of apps. go down a little bit and press show all apps then scroll down untill you see Music. Press music and it should have an edit button, and then press delete data. But this clears your entire music library, so if you have songs that you do want on your ipod you will have to recheck them in itunes and resync your IPod. This applies to videos too, so if there are any music videos that won't delete, you can try this. I hope this helps!