Ahh iv figured out a way to do this:
<?php
$args = array(
'post_type' => 'classes',
'orderby' => 'title',
'posts_per_page' => -1
);
$the_query = new WP_Query( $args );
$unique_titles = array();
if( $the_query->have_posts() ) : while ( $the_query->have_posts() ) : $the_query->the_post();
$title = get_the_title();
if( ! in_array( $title, $unique_cities ) ) :
$unique_titles[] = $title;
?>