I'd like to remove Custom field name (even if i disabled it in its own custom field is showed anyway) and the black line over.

Solved:
In /css/override.css type like this:

#FlexibleProductDetailsPage span.product-fields-title {
border-bottom: 0px solid #333;background: #ffffff!important;
font-size: 0px!important;
}

Thanks for updating your own topic.

Case solved, topic is closed.

regards.