Discuss your plan with your hair stylist. Since achieving the Wave Nouveau hairstyle most likely involved a hair stylist to help you figure out what to apply when, tap her knowledge now to get advice on how to best manage this new transition. Discuss what you want to do with your hair next. Since you've been curly for a while, you may want to opt for a more relaxed, straight look this next time around, or you may want to go for a wig or a weave during the transition.
Stop using your Wave Nouveau Coiffure products. Since the line of moisturizers, shape lockers, shape transformers and other products is what helps your hair achieve that look, stopping that regimen will begin to undo what's been done.
Allow your hair to grow out, or cut off the wave nouveau style all together and start with an almost-bald head. While this may sound scary, the upside here is that you have the option of getting a weave of longer, straighter locks, or making any number of fun additions to your head during the "grow out" phase. According to Soft Sheen, the maker of Wave Nouveau, the wave nouveau process is incompatible with relaxers, so you're going to have to wait until your old hair is gone before you can start fresh.
Have your hair relaxed, weaved or otherwise styled by the stylist of your choice, once your hair has grown out to be long enough to style the hair that is not wave nouveau.
As you grow your hair out, be sure to keep it well-moisturized so that you don't end up with dry, brittle new hair growth.