Of note, the Logic Board is not a user-serviceable part, which means the only way they would have sent you one is if you're a certified technician, and working for someone with GSX access. The idea that you don't know this all already and don't have access to the Apple's systems to find out all you need to know is really quite unbelievable. I don't know what you're doing exactly, but your story isn't really checking out so far. The answer remains the same regardless of your intentions, however. There is absolutely no way of removing a serial number once it's been flashed to a board, outside of Cupertino or whatever other secret location they use for that process (it probably requires a hardware tool of some type).
jW
