How to Hide the "Dynamic home length" Admin Menu

function plt_hide_dynamic_home_length_menus() {
	//Hide the "Settings → Dynamic home length" menu.
	remove_submenu_page('options-general.php', 'dynamic-home-length');
}

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

Where do I put this code?