(Moved this thread over here for http://photosynth.net/userprofilepage.aspx?user=klaatu)
Looking around the site and forums, I could not quickly find document describing how to use the application and how to edit synths already uploaded. If I missed something, please add a comment to this forum, since other users may look here first, as I did.
Likewise, the .pdf document did not answer many of my questions about account and application.
Delete an uploaded synth
* Log in.
* Click on your username in the upper right area of the page.
* On your profile page, click the "My Synths tab" to view all your synths.
* Click the X in the upper right corner to delete the synth.
(adapted from another forum comment)