How do I remove a tv show from Ipod?

Hello,

I downloaded a few episodes of a tv show onto my Ipod touch via a wifi connection when I was without my computer. Now that I have watched them and have synced the Ipod with the Itunes... How do I remove the shows from the Ipod but keep them in the Itunes library? They are taking up enormous amount of space on the Ipod itself.

Thanks for any help.

John