How do I delete photos from iPod 5's photos app?

Hello.

I recently transfered my photos from iPhoto on my Macbook Air to my iPod 5th Generation. Now I want to delete this pictures and every time i click on the photos, there is no trash bin icon or anything there to delete them. Is there a way to delete/transfer the picture back on my laptop? Or are the picture just stuck o the ipod?

Any help is appreciated.