How do you eject ipod when using the Apple USB Power Adapter?

I just brought a new ipod nano. I'd like to buy a Apple USB Power Adapter to charge the ipod. I am not sure how to disconnecting safely without damaging the files on the ipod because the manual said that you are not suppose to disconnect the ipod without ejecting it from itune.

"Don't disconnect the ipod nano if you see the Connected or Synchronizing message.To avoid damaging files on ipod nano, eject ipod nano before disconnecting the cable if you see one of these messages.