how do I delete pictures that were synced onto my ipod?

When I got my iPod I took loads of pictures and to create space I put them on my computer so I can take more pictures and get more apps.

Now the problem is once I transfered them from my iPod to computer, every time my iPod syncs it takes the pictures from my computer onto my iPod and now they aren't on the camera roll, they are on these albums with the albums marked as dates.

I cannot find a way to delete these pictures in albums from my iPod so how do I delete them? I already tried deleting the original pictures from my computer but it won't work!

HELP ME PLEASE I NEED SPACE AND ALL THESE PICTURES ARE USING UP THE SPACE. THANKS.