Q. I have forgotten the UEFI password for my Surface Pro 3 device. How do I reset it?
A. You can't and this is by design as if there was some way to reset the password it would not be a viable way to secure the device. The only way to reset a forgotten UEFI password is to send the device back to the Microsoft service center who can reset it. The morale of the story is if you set a UEFI password make sure you write it down somewhere safe.