Destroying php session when clicked back in browser with ajax

I have two files index.php (first) and second booking.php (second) ,what I want is when someone moves from booking .php to index.php session gets destroyed.

What I have tried so far is ,destroying session with ajax

Here is my relevant code in booking.php file

$(window).on("popstate", function (event, state) {

    $.ajax({
          type: 'GET',
          url: 'logout.php',
          async:yes,
          success: function(msg) {
              if (msg == 'loggedOut') {
            window.location.href = 'index.php';
              }
          }
      });
    });

And here is my logout.php file

<?php
session_start();
session_destroy();
echo "loggedOut";
?>

Is there any possible way to do above thing I mentioned and if yes then where I should my ajax code ,in booking.php or index.php ! Thanks in advance