Years ago, when I used to restore vintage Barbies for a living, I used to use clearasil (acne drying gel) and dab it on, and let it sit until it dried out. It rarely only took a few applications, it usually took many times and a month or so of waiting. There used to be a few products that were sold by restoration supplies that were specifically meant to treat vinyl doll green ear that worked the same way. I forget the names, but they can be found at Barbie or doll swaps or conventions. Regardless of what you use, it takes a long time, and there is always a really faint line of demarcation that will never go away. So, if you have green ear, unfortunately I've never seen any method that removes it completely, and leaves no sign of the fact that it used to be green. I have a platinum Swirl that has been in a box for ten years waiting for me to do something about her green ears, but I just haven't gotten around to doing anything about it since I know she'll never be the same. It's been a while since I checked, maybe in the last few years someone has come out with something that actually removes it completely- I'd like to hear about it!
*No matter what, don't ever put metal earrings(unless they're stainless steel) back into a green ear treated doll, because the green will come right back!