By default Drupal displays the web site name along with logo.
I’m still exploring the easiest way to disable it being displayed.
One quickest way is to comment out it from the .php file. To do so open page.tpl.php file in your theme folder and search for following line
<?php print $site_name; ?></a>
Modify this line as below
<?php //print $site_name; ?></a>