I found out that you can't delete photos individually from the Photo Stream folder on the phone. The only option for deleting is to go through the iCloud web browser interface and reset the Photo Stream (account settings, Advanced), which removes ALL photos. I think this is a pretty major fault. And to add insult to injury, I've been trying all day to reset the Photo Stream and keep getting the error message: Could Not Reset Your Photo Stream. Your Photo Stream could not be reset at this time due to a server error. Try again later.