1) By totally destroying Samsung, AT&T and Verizon. (They all sold out.) If you can figure out an unlocked bootloader, you can probably make enough money in prizes to take a year off.
2) To unroot, go into SuperSu/Settings, scroll down to the Cleanup section and press Full unroot. Or just flash the stock 4.4.2 if you want to return the phone to out-of-the-box - the one for your country/carrier should be on SamMobile Firmwares.