If you are asking about deleting it from an Ipod do what Ignotus said.
Transfering from an Ipod to a computer is slightly more difficult, especially if you want to avoid downloading random freeware programs that are out there ( a good idea!). You have to do a bulk transfer of all the music I'm afraid.
This should work
#1 In Control Panel, Portable Media Devices, double-click your iPod.
#2 In the Tools menu -> Options, in the View Tab, check "Show hidden files and folders."
#3 Navigate to the Music folder. On my 2nd gen 'pod, the full path is
Portable Media Devices\GINA'S IPOD (F

\iPod_Control\Music
# 4Select all the music folders, and drag and drop them into a folder on your hard drive, or directly into iTunes.
It's just going to be a bunch of gibberish, so have iTunes automatically order it and it wil show up all nice and pretty.