Nope. The photos sync'd via iTunes have to be removed via iTunes. Unlike music, photos do not live in the iTunes library. They live in iPhoto or Aperture on a Mac or in a Photos folder on a PC. The path to add or remove them is directly linked to the sync process. You can delete Camera Roll photos or Photo Stream photos. Camera Roll photos because they live only on your iPhone until you import and delete them from the device. Photo Stream photos because they live in iCloud, and although you may have them set up to automatically upload and import to iPhoto or Aperture, they also live separately in iCloud. If you delete a Camera Roll photo that you have already imported to your computer, it deletes it only from the phone. If you delete a Photo Stream photo that you have automatically imported to iPhoto or Aperture, then it only deletes it from your phone and from your live Photo Stream. In both of those cases, those photos also reside, under a separate path, in your Photo Library.
That's just the way it works for now. We will have to see what happens when the new Photo App comes out.
Cheers,
GB