IgniteWoo.com Team on "[Plugin: WooCommerce - excelling eCommerce] Where are product type forms being loaded from?"

The product types are loaded in

woocommerce/admin/post-types/writepanel/writepanel-product_data.php

In there you will find this:

$product_type_selector = apply_filters( 'product_type_selector', array(
		'simple' 	=> __( 'Simple product', 'woocommerce' ),
		'grouped' 	=> __( 'Grouped product', 'woocommerce' ),
		'external' 	=> __( 'External/Affiliate product', 'woocommerce' )
	), $product_type );

So as you can see, you need to create a filter to add / remove types.