my-pmpro-cancel-subscription-on-denial.php

<?php
/**
 * Cancel membership level and subscription at payment gateway when a member is denied.
 *
 * You can add this recipe to your site by creating a custom plugin
 * or using the Code Snippets plugin available for free in the WordPress repository.
 * Read this companion article for step-by-step directions on either method.
 * https://www.paidmembershipspro.com/create-a-plugin-for-pmpro-customizations/
 */
function my_pmpro_cancel_subscription_on_denial( $user_id, $level_id ) {
	// Get the user's order.
	$order = new MemberOrder();
	$order->getLastMemberOrder( $user_id, 'success', $level_id );

	 // Cancel the membership level, which will also cancel any subscriptions.
	if ( ! empty( $order ) && ! empty( $order->id ) ) {
		pmpro_cancelMembershipLevel( $level_id, $user_id, 'denied' );
	}
}
add_action( 'pmpro_approvals_after_deny_member', 'my_pmpro_cancel_subscription_on_denial', 10, 2 );