Removing the first 8-10 letters from a post?

This is a new query loop that I use that shows the latest ten post titles/permalinks in the category mycategoryname and strips the first 15 characters from all of the titles.

<?php $my_query = new WP_Query('category_name=mycategoryname&showposts=10'); ?>
<?php while ($my_query->have_posts()) : $my_query->the_post(); ?>
<a href="https://wordpress.stackexchange.com/questions/14120/<?php the_permalink() ?>" title="Permanent Link to: <?php the_title_attribute(); ?>">
<?php $mytitle = get_the_title(); $mytitle = substr($mytitle,15); echo $mytitle; ?></a>
<?php endwhile; ?>

If you need to select which posts to strip either 8 or 10 characters, you’d have to select them by some sort of criterea and alternate that character number.