typerlc

Or … another approach … create a simple plugin, and add the following filter:

add_filter('bogo_language_switcher_links', 'my_bogo_language_switcher_links_filter');
function my_bogo_language_switcher_links_filter($links, $args)
{
        foreach ( $links as $key => $link ) {
                if ( $link['locale'] == 'en_US' ) {
                        unset( $links[$key] );
                        break;
                }
        }
        return $links;
}