session_unset

I was having a problem clearing all session variables, deleting the session, and creating a new session without leaving old session stuff behind in all browsers. The below code is perfect for a logout script to totally delete everything and start new. It even works in Chrome which seems to not work as other browsers when trying do logout and start a new session.
<?php
 session_start();
 session_unset();
 session_destroy();
 session_write_close();
 setcookie(session_name(),'',0,'/');
 session_regenerate_id(true);
?>

The difference between both session_unset and session_destroy is as follows:
session_unset just clears out the session for usage. The session is still on the users computer. Note that by using session_unset, the variable still exists. session_unset just remove all session variables. it does not destroy the session....so the session would still be active.
Using session_unset in tandem with session_destroy however, is a much more effective means of actually clearing out data. As stated in the example above, this works very well, cross browser. session_destroy is destroy the session. session_destroy() to kill all session information.....This is the more secure function to use.

The solution provided by tim at leethost dot com is nice but you must check a active session first, because else you fill the logs with PHP Errors or Notices depending on your settings. I use it as a function, and it works smooth. 
```php
 /** @return void */
 public static function sayonara():void
 {
 if (session_status() !== PHP_SESSION_ACTIVE) :void
 {
 session_start();
 session_unset();
 session_destroy();
 session_write_close();
 setcookie(session_name(), '', 0, '/');
 session_regenerate_id(true);
 } 
 }
 sayonara();
```