How to Hide the "WC Ship Estimate" Admin Menu

function plt_hide_wc_ship_est_menus() {
	//Hide the "Settings → WC Ship Estimate" menu.
	remove_submenu_page('options-general.php', 'wc-ship-est');
}

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

Where do I put this code?