[doc55]

Thank you Dave for your helpful reply.
Here is the final and functioning code for others, if they need one:

PHP Code:

//Init the vBulletin system
require_once('/forum/includes/vb5/autoloader.php' );
vB5_Autoloader::register('/forum' );
vB5_Frontend_Application::init( 'config.php' );

//Get user info
$vb_userInfo = vB_Api::instance( 'user' )->fetchUserinfo();

//Log out URL
$logout_url = '/forum/auth/logout?logouthash=' . $vb_userInfo[ 'logouthash' ];
header( "Location: $logout_url" ); 


One question, with the above code, the user is logged out then redirected to the forum home. My forum is installed in mydomain.com/forum. How can I redirect users after logout to mydomain.com?

--------------- Added [DATE]1567529927[/DATE] at [TIME]1567529927[/TIME] ---------------

Maybe I should ask the question differently.
Is it possible to execute the as a function or in the background, instead of redirecting to it as a URL?

PHP Code:

$logout_url = '/forum/auth/logout?logouthash=' . $vb_userInfo[ 'logouthash' ];