GBS: Filter Checkout Registration Panes

functions.php

add_action('init','filter_gb_controllers', 500);
function filter_gb_controllers() {	
	remove_all_filters('gb_checkout_account_registration_panes');
	add_filter('gb_checkout_account_registration_panes','remove_contact_info_pane');
}
function remove_contact_info_pane( $panes ) {
	//Make it a minimal registration since the checkout process will save the billing info.
	unset($panes['contact_info']);
	return $panes;
}