How to remove box around sidebar?

Hi!

How do I remove the box around my sidebar?
You can see a picture here:

https://www.billigste-internet.dk/wp-content/uploads/2013/02/box-around-sidebar.png

It says the following in my:

sidebar-custom.php:

<?php
global $sidebar_choice;

?>
<div id="sidebar-wrapper" class="one-third column">
<?php if(is_page_template('template-sidebarleft.php')){ ?>
<img class="sidebar-shadow-l" src="<?php echo get_template_directory_uri() ?>/images/sidebar-shadow-l.png" />
<?php }else{?>
<img class="sidebar-shadow" src="<?php echo get_template_directory_uri() ?>/images/sidebar-shadow.png" />
<?php }?>
		<?php if ( !function_exists('dynamic_sidebar') || !dynamic_sidebar($sidebar_choice) ) : ?>
    <?php endif; ?>
</div>

And in my sidebar.php:

<?php if ( !function_exists('dynamic_sidebar') || !dynamic_sidebar('Blog Single') ) : ?>
    <?php endif; ?>

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Hope someone can help ??