That actually appearing from your themes template and not bbPress’ templates.
If you open up your page.php
template of your theme (Or whatever the primary temmplate is) you will see something similar to this code:
<div class="entry-author-meta">
<p class="author-name">Published by
<span class="author vcard"><a class="url fn n" href="#" title="#">#</a></span>
</p>
<p class="author-description">
</p>
</div>
Now make a copy of your page.php
template (or again the main template your theme uses) and rename the this to bbpress.php
open up the bbpress.php
in a text editor and remove the section of code that I listed above.
bbPress will now use this template rather that your themes default template.