Sliced Invoices: remove rate field from showing

functions.php

add_filter( 'sliced_invoice_line_items_output', 'sliced_invoice_line_items_output_20171013' );
function sliced_invoice_line_items_output_20171013( $output ) {
	// remove rate field from showing
	$regex = array(
		'#<th class="rate">(.*?)</th>#',
		'#<td class="rate">(.*?)</td>#'
	);
	$output = preg_replace( $regex, '', $output );
	return $output;
}