How to Hide Table of Contents Plus Admin Menus

function plt_hide_table_of_contents_plus_menus() {
	//Hide the "ToC+" menu.
	remove_menu_page('table-of-contents');
	//Hide the "ToC+ → Settings" menu.
	remove_submenu_page('table-of-contents', 'table-of-contents');
	//Hide the "ToC+ → About Us" menu.
	remove_submenu_page('table-of-contents', 'table-of-contents-about');
}

add_action('admin_menu', 'plt_hide_table_of_contents_plus_menus', 1000);

Where do I put this code?