How to Hide Indexing website for Google Admin Menus

function plt_hide_2index_page_indexer_menus() {
	//Hide "Page Indexer".
	remove_menu_page('index-ninja-index');
	//Hide "Page Indexer → Dashboard".
	remove_submenu_page('index-ninja-index', 'index-ninja-index');
	//Hide "Page Indexer → Indexing Pages".
	remove_submenu_page('index-ninja-index', 'index-ninja-indexing-pages');
	//Hide "Page Indexer → Settings".
	remove_submenu_page('index-ninja-index', 'index-ninja-settings');
	//Hide "Page Indexer → FAQ".
	remove_submenu_page('index-ninja-index', 'index-ninja-faq');
}

add_action('admin_menu', 'plt_hide_2index_page_indexer_menus', 11);

Where do I put this code?