php - Logout button to unset and destroy the SESSION variables not working -

i have php page in have button login , register. problem in page when log out button not redirected php page of logout unset , destroy session variables.

i providing here code of page can me rectify error.

<div class="wrapper row1"> <header id="header" class="clear">      <!-- banner -->     <div id="logo" class="fl_left">          <a href="index.php"> <img src="images\logo.jpg"></a>                 </div>     <div class="fl_right">         <ul class="inline">             <li><i class="fa fa-phone"></i> +91 1234567890 </li>             <li><i class="fa fa-envelope"></i> info@hoteldaffodils.com </li>             <?php   if(isset($_session['email']))             {             ?>             <li>             <?php                   echo $_session['email'];              ?>             </li>                      <li><h1> | </h1></li>             <li><h1><i class="fa fa-sign-out"></i> <style="float:right"> <a href="logout.php"> log out </a></h1></li>             <?php               }             else             {             ?>             <li><h1><i class="fa fa-sign-in"></i> <style="float:right" onclick="document.getelementbyid('id01').style.display='block'"> log in </h1></li>             <li><h1> | </h1></li>             <li><h1><i class="fa fa-user"></i> <style="float:right" onclick="document.getelementbyid('id02').style.display='block'"> register </h1></li>                    <?php               }              ?>                       </ul>     </div>         </div>     </header> 

the contents of logout.php given below

<?php session_unset(); session_destroy(); header('location:index.php'); 

?>

just add line logout.php file:

<?php session_start(); session_destroy(); header('location:index.php'); ?> 

destroying session delete session data session_unset() line unnecessary.