function plt_hide_post_extra_menus() {
//Hide "Post Extra".
remove_menu_page('pxtr-admin');
//Hide "Post Extra → Post Extra".
remove_submenu_page('pxtr-admin', 'pxtr-admin');
//Hide "Post Extra → Contact Us".
remove_submenu_page('pxtr-admin', 'pxtr-admin-contact');
//Hide "Post Extra → Support Forum".
remove_submenu_page('pxtr-admin', 'pxtr-admin-wp-support-forum');
//Hide "Post Extra → Upgrade".
remove_submenu_page('pxtr-admin', 'pxtr-admin-pricing');
}
add_action('admin_menu', 'plt_hide_post_extra_menus', 1000000000);