Polymer Notes, Creases, How To...

There really isn't anything you can do to remove the creases.

Polymer banknotes don't melt when heated, but they do shrivel up. You'll end up with a banknote that's only a quarter of the size of the one you started with, and it will look far worse than simply having a couple of folds.

One of the things the general public complained about when we switched from paper to polymer notes is the tendency of polymer to "remember" it's folds much more than paper does. The only thing you can do is stick it in your banknote album and keep it nice and flat for as long as possible.

The "heavy books" trick will work too, but you'll have to keep them in there for much longer than a similarly bent paper note to get the same effect.