Manually deleting files from your ipod - How?

Ok this problem have a very simple answer.

I have an ipod and I manage my music and videos manually. Getting stuff on my pod is easy using this method but how can manually delete a song or movie from your pod? When the pod is connected you can see the contents but they are greyed out and I simply cannot see any way of manually deleting a file which is very frustrating.

Any ipod gurus out there who can help?

Thanks

uncheck the songs in your library and click update ipod

This method is not managing manually though, it is synching surely?

I also have files still on my pod but not in my itunes that I want to keep

All you should have to do is make sure that your iPod is selected in iTunes, then simply highlight the item you wish to delete and then hit the Delete key.