Delete learndash user infos after a certain date

Delete learndash user infos after a certain date.php

<?php
define( 'WP_USE_THEMES', false );
require( 'wp-blog-header.php' );

$usermeta = get_user_meta( 354, '_sfwd-quizzes', true );
$new = array();

foreach ($usermeta as $key => $value) {
	if ( $value['time'] < 1476545002 ) 
		array_push($new, $value);
}

update_user_meta( 354, '_sfwd-quizzes', $new);
d($new);
ddd( $usermeta );