I am not really familiar with practiceboard so I am not sure how to go about deleting it there. I think it would be safer to keep the html in a notepad file on your computer as a backup (that is where mine is).
I was able to paste your html into my auctiva account and look at it and save it (don't worry I will be deleting once I get back to my templates ) so I really question how secure it is. I would delete the link to Practiceboard you have in your original post.
Maybe someone can shed some light on how secure templates are in Practiceboard.