I think nobody except chinese luthiers can give you a professional advise on how to remove it.
Just for your information the soundboard is likely to be paulownia wood and there should be two
thick braces under the soundboard which are glued to the back, too !
If you decide to cut it off it will not be loose after you have cut through the binding.
It is very difficult (I think) to get it off without ripping it appart.
So good luck and btw I never had a pipa in my own hands, I cannot guarantee that this info is right