Is it possible to delete photos once they have been uploaded - eg the ones that have not been included in a synth as this would allow for extra synths to be uploaded when running out of space.

Due to how we build the sets, there's no way to take individual photos out of a synth. You'd need to resynth without the ones you don't want. With 20gb there's space for a lot of photos.

that is very interesting, how do you build the sets? I hope if you can't truly delete or fake delete (hide) the photo or destroy it in question the very essence of the foundation of the sets is very probable. I hope there is some way to find a loop hole around these kind of situations. :)

As far as I understand, currently there are no local remains of a Synth after the upload. Might be an idea to change that, keep a Synth local too and provide for functionality to improve the Synth locally and update the online version.