Is there an option to edit a symbol created with InstaBuild?

Right now there is no way to edit the part on SnapEDA. So you'd have to delete and do it again, or download and modify within your PCB design software. Will let our engineers know that this would be a useful feature to add.

Never mind, I was looking for a "Delete" button but I just noticed the "Re-Build Part" link at the top right of the screen, and in so doing answered my own question.

I may be missing something, but assuming one is in such a situation, how does one go about deleting the symbol and starting the instabuild process over?