Force disable PP Reference Transactions

disable-pp-rt.php

<?php
/**
 * Plugin Name: Disable PayPal Reference Transactions
 * Plugin URI:
 * Description: Force the store to use PP Standard. Helps to test both sides of PayPal :+1:
 * Version: 1.0
 * Author: Matt Allan
 * Author URI: http://prospress.com
 * License: 
 */
add_filter( 'wooocommerce_subscriptions_paypal_reference_transactions_enabled', '__return_false' );