How do I sell my games that I have created for RPG Maker 2? By getting their permission?

I don't know the answer to that but what are you trying to sell? The game idea (like to a professional company), copies of the saved file (like to gamers who want to play it), or something else?

Out of all the RPGMs for the consoles I think the only one that addresses selling them is RPGM1 which has a legal statement in the instruction booklet about your rights.

It says that you can sell them but it also says (I think) that this doesn't mean they can be used in a commercial product? So I don't really understand what that means and I don't know if it would necessarily be the same for RPGM2.

Nobody's gonna buy it.

What Duel said. Games made on RPGM1-3 aren't worth selling. It's way too easy to copy games, and no matter what you do, there will always bee too many similarities between it and other such products. Only RMXP and RMVX would you have a chance at selling creations, and even then, it would have to be something pretty spectacular (ie, uses none of the default graphics or music).

Again it depends on what he is trying to sell. It is one thing to say "don't get your hopes up". But it is another to say that they aren't worth selling. Maybe he could find a buyer depending on what exactly he is trying to sell. Of course in this community we encourage posting them for free. You could still use them on a resume or in a portfolio as evidence of your talent. But if you can sell them then more power to you.