Remove double search bar

Hi

I managed to add a search bar at the secondary menu using the code below:

//Search
add_filter( 'wp_nav_menu_items','add_search_box', 10, 2 );
function add_search_box( $items, $args ) {
    $items .= '<li>' . get_search_form( false ) . '</li>';
    return $items;
}

But now theres an extra one on the top bar. Please tell me how to remove that extra one or make it show only on the secondary nav.

Thanks!