you can't delete the photo's or albums from the ipod touch directly, but you can choose the checkmark on the synch page on itunes that says synch only checked music and photos, and if you uncheck some of your photo albums, itunes will automatically delete the photos that you unchecked the next time you synch your ipod with the computer.
If, while connected, you unsync your ipod from the pictures, then the sync will remove from your ipod any and all pictures and albums that you chose to unsync. it will NOT delete them from your computer, only your ipod.