How to Hide the "All 404 Redirect to Homepage" Admin Menu

function plt_hide_all_404_pages_redirect_to_homepage_menus() {
	//Hide the "Settings → All 404 Redirect to Homepage" menu.
	remove_submenu_page('options-general.php', 'all-404-redirect-option');
}

add_action('admin_menu', 'plt_hide_all_404_pages_redirect_to_homepage_menus', 11);

Where do I put this code?