function plt_hide_piklist_menus() {
//Hide "Piklist".
remove_menu_page('piklist');
//Hide "Piklist → About".
remove_submenu_page('piklist', 'piklist');
//Hide "Piklist → Settings".
remove_submenu_page('piklist', 'piklist-core-settings');
//Hide "Piklist → Add-ons".
remove_submenu_page('piklist', 'piklist-core-addons');
}
add_action('admin_menu', 'plt_hide_piklist_menus', 11);