go to the photos tab in itunes and and select the folder of where you keep photos of your own that you would be putting on.(or an empty folder) and resynch. If not. Go to my computer and find ur iPod.
right click once ur in the ipod and properties then one of the tabs should have a list with check boxes scroll down till you see show hidden files and folders, check it and hit ok....some folders should pop up....then just search for the photos folder and delete