The white-space is created because of the way you’ve formatted your code.
Every time you close php ?>' and then open it again on a new line<?php `, the page outputs that new line. All of those open/close php tags are unnecessary.
<?php
$colore = get_field('colore');
if( $colore ):
foreach( $colore as $colore ):
?><span class="color-<?php echo $colore; ?>"></span><?php
endforeach;
endif;
?>
