Destroy user session in php

<?php
session_start();
include("connect.php");
$id=$_SESSION['id'];
$result ="UPDATE tbl_user SET status = 'inactive' WHERE empID = '$id' ";                   
$rs2 = mysql_query($result) or die("Invalid Query <br>$result");
//store to test if they were log in
$old_user=$_SESSION['user'];
unset($_SESSION['user']);
session_destroy();

header('Location: ./index.php');
?>