How to disable PHP session cookie?

SetEnv session.use_cookies='0';

ini_set('session.use_cookies', '0');

<?php
// Initialize the session.
// If you are using session_name("something"), don't forget it now!
session_start();

// Unset all of the session variables.
$_SESSION = array();

// If it's desired to kill the session, also delete the session cookie.
// Note: This will destroy the session, and not just the session data!
if (isset($_COOKIE[session_name()])) {
    setcookie(session_name(), '', time()-42000, '/');
}

// Finally, destroy the session.
session_destroy();
?>

if( !array_key_exists('sessionid', $_POST) ) {
    // recreate the sessionid
    $sessionid = md5(rand().' '.microtime()); // Or something
} else {
    $sessionid = $_POST['sessionid'];

session_id($sessionid);
session_start();

<input type='hidden' name='sessionid'><?= session_id() ?></input>