There are several ways to do this, one involves using a counter so that you don’t add a comma after the last one.
<?php
$terms = get_field('location_type');
if( $terms ):
$total = count($terms)
$count = 1;
foreach( $terms as $term ):
?>
<a href="<?php
echo get_term_link( $term ); ?>"><?php
echo $term->name; ?></a>
<?php
if ($count < $total) {
echo ', ';
}
$count++;
endforeach;
endif;
?>
