I found this from just a Google search (Source)
You have to change met value keys as you want. However, it is highly recommend to take a DB backup before running this code.
<?php
function delete_useless_post_meta() {
global $wpdb;
$table = $wpdb->prefix.'postmeta';
$wpdb->delete ($table, array('meta_key' => '_edit_last'));
$wpdb->delete ($table, array('meta_key' => '_edit_lock'));
$wpdb->delete ($table, array('meta_key' => '_wp_old_slug')); }
add_action('wp_logout','delete_useless_post_meta');
?>