Connect your ipod to your PC and open up itunes.
Your iPod's name should appear in itunes.
Click on it with your mouse.
You should see now all the songs in the iPod.
Select the songs you want to delete and delete them.
Then Sync your iPod - & the songs will be gone.
Then hook up the iPod to the computer and let in sync, those songs should be gone when it completes.
You can keep a song on iTunes and delete it off your ipod by un-ticking the little box next to every song you wish to be deleted off your ipod. Apple have added a delete button the ipod touches however, and iPhone 4's
Unfortunately, it's impossible. You must use iTunes to delete any songs. It can't work any other way. I sure hope Apple adds a delete button soon!
You can't, you have to go to the website you got them from.