public static function remove_contact(int $userid, int $contactid) {
        global $DB;

        if ($contact = self::get_contact($userid, $contactid)) {
            $DB->delete_records('message_contacts', ['id' => $contact->id]);

            $event = \core\event\message_contact_removed::create(array(
                'objectid' => $contact->id,
                'userid' => $userid,
                'relateduserid' => $contactid,
                'context' => \context_user::instance($userid)
            ));
            $event->add_record_snapshot('message_contacts', $contact);
            $event->trigger();
        }
    }