input type button

[Justino]

<form method="post" action="">
<input type="hidden" name="delete" value="<?php echo $row['img']; ?>" />
<input type="submit" value="Rimuovi immagine" />
</form>

<?php
if (isset($_POST['delete'])) {
  $img = $_POST['delete'];
  $f->deleteImage($img, 'prodotti')
}
?>

Altrimenti devi utilizzare AJAX.