In the unite folder you should have a file called “sidebar.php”, open it and you will find code that looks like this:
<?php if ( ! dynamic_sidebar( 'sidebar-1' ) ) : ?>
<aside id="search" class="widget widget_search">
<?php get_search_form(); ?>
</aside>
<aside id="archives" class="widget">
<h1 class="widget-title"><?php _e( 'Archives', 'unite' ); ?></h1>
<ul>
<?php wp_get_archives( array( 'type' => 'monthly' ) ); ?>
</ul>
</aside>
<aside id="meta" class="widget">
<h1 class="widget-title"><?php _e( 'Meta', 'unite' ); ?></h1>
<ul>
<?php wp_register(); ?>
<li><?php wp_loginout(); ?></li>
<?php wp_meta(); ?>
</ul>
</aside>
<?php endif; // end sidebar widget area ?>
As you can see there are three <aside> elements, one search, one archive, and one meta. These three are only visible if you have added no widgets in the sidebar. In other words, it is the default content. Change it to something like this if you want it empty:
<?php if ( ! dynamic_sidebar( 'sidebar-1' ) ) : ?>
<!-- everything inside the if clause has been removed -->
<?php endif; // end sidebar widget area ?>
