CMS Mastering Development Wordpress

Calling a function of a plugin from wordpress theme header file

wp-content/plugins/ultimate-member/includes/core/class-permalinks.php namespace um\core; class Permalinks { function __construct() { add_action( ‘init’, array( &$this, ‘activate_account_via_email_link’ ), 1 ); } } I want to call this function ‘activate_account_via_email_link’ from wordpress/theme/header.php My code so far : $action = new um\core\Permalinks; $action->activate_account_via_email_link(); The error : Fatal error: Uncaught Error: Class ‘um\core\Permalinks’ not found in /home/xyzz/public_html/xyz/wp-content/themes/university/header-frontpage.php:5 Stack trace: #0