Problems with removing songs from my ipod.

Hi! I've read the readme to my ipod nano, and it says there, if I got it to automatically syncronising songs, it transfers everything in my library to my ipod, and if I remove something from my library and then sync again, it will delete that song from my Ipod too.

I added a song to my library, then synced, and the song did get to my ipod, but when I removed the song from my library and synced, it was still on my ipod. My question is, how do you delete songs from your Ipod, when it's set to automatically update?

Thanks!