EDD remove first name from checkout

file.php

<?php // DO NOT COPY THIS LINE

function pw_edd_purchase_form_required_fields( $required_fields ) {
	unset( $required_fields['edd_first'] );
	return $required_fields;
}
add_filter( 'edd_purchase_form_required_fields', 'pw_edd_purchase_form_required_fields' );