How to Hide Download List Block with Icons Admin Menus

function plt_hide_download_list_block_with_icons_menus() {
	//Hide "Download List Icons".
	remove_menu_page('edit.php?post_type=dl_icons');
	//Hide "Download List Icons → All Icons".
	remove_submenu_page('edit.php?post_type=dl_icons', 'edit.php?post_type=dl_icons');
	//Hide "Download List Icons → Add new Icon".
	remove_submenu_page('edit.php?post_type=dl_icons', 'post-new.php?post_type=dl_icons');
	//Hide "Download List Icons → Iconsets".
	remove_submenu_page('edit.php?post_type=dl_icons', 'edit-tags.php?taxonomy=dl_icon_set&post_type=dl_icons');
}

add_action('admin_menu', 'plt_hide_download_list_block_with_icons_menus', 15);

Where do I put this code?