$id = $_GET['id'];
if($id) {
    $file_handle = fopen("testimonials.csv", "w+");
    $myCsv = array();
    while (!feof($file_handle) ) {
        $line_of_text = fgetcsv($file_handle, 1024);    
        if ($id != $line_of_text[0]) {
            fputcsv($file_handle, $line_of_text);
        }
    }
    fclose($file_handle);
}