I have many games via Steam.. but for OOTP, I've just always purchased directly from OOTP.
You can uninstall from Steam and install the full version (I'm guessing that's possible?) from OOTP. Did you get a serial number from Steam? You would need that to install the non-Steam version (again, if that's possible?).
Most people here are super helpful, so don't take some posts to heart.
