Just reflash it with the "back to stock" rom and it will be unmarried. You can verify by checking the ECU status with Osiris, when the tune is on the ECU is shows up as "Uprev flashed ECU'.. once you reflash back to stock it will just display the ECU part #.
After that you can also doublecheck that the license went back on the cable by clicking on the "cable management tab" in Osiris, it will tell you if the license is on the ECU or on the cable.