Did the leaves fall off? Something not working right? Let us know how we can improve the Photosynth experience.
You can actually delete your synths by logging in and clicking your username in the upper right area of the page. Once on your profile page, click the My Synths tab to view all your synths. Each card has a little X in the top right corner. Clicking that X will delete that synth.
Wouldn't merging the yoursynth and profile page into one url help with your issue. It could allow edits if you are signed in, otherwise it is your public profile page.
What a fantastic idea Nathan! Photosynth should hire you to make such things... :)