Problem with removing unwanted music

Some of my bf's music transferred to my iPod Touch 4G when I had set his iPhone 4s to my computer. However, I have now deleted the songs of his I DON'T want off my iTunes library, deleted them from my computer, and yet, when I sync my iPod to my computer, the songs HAVEN'T been removed! I have synced about 3 times to find them still on there. I shut off home sharing, the whole nine yards.

Please help! I really want his stuff off my iPod!!!!