How do I change the main external editor from PS CC to PS 6?

I put a trial version of PS CC on my computer and Lightroom 4 has changed the main external editor to the CC trial version. I don't want this to happen and I don't want PS6 to be an "Additional External Editor." I want the main editor to be PS6 at all times but I cannot seem to change this.

Is this possible or is the only solution to get rid of the trial version of PS CC? If I trash the trial version of PS will Lightroom 4 automatically "find" PS6 again.

Thanks