Removing product ID from invoice

I am trying to remove the product ID from my invoice. I read that I need to remove the:

.''.$product->order_product_code

from the Files "invoice" and "form" in the View "order". I found them and deleted those entries.. but the product ID still shows up on the invoice.

Hi,

Do you have removed the order_product_code in the good template ?
Try to remove it in your backend template, view "order / invoice".