Following instructions are provided without any warranty, and may even get you in trouble legally. The instructions are provided for testing, learning, preventing e-waste, and should be use with care. We (including contributers + commentators) are not responsible for any damage to your device(s) or any legal issues.
Instructions have been moved to https://github.com/francoism90/asus-router. :)
I think you need to change the country, as the chipset/firmware probably does some testing if it even can be disabled.
You don't have to change the transmit power. It's there as a reference.
Just a reminder: even when setting a different country or TX-power, it doesn't mean it actually works. The Intel chipsets most people have on their end devices, does some hidden checking and makes it really difficult to workaround certain 'hacks'.
So the given instructions, may or may work. It depends on your setup and maybe a bit of luck.