To find the template - vboptions > General Settings > Add Template Name in HTML Comments > set to Yes . Then go back to your page and view the source code and you will see the name of the template called around your part of the code. Do that, and you'll find the template is "threadadmin_logbit" Go in to edit it, and just replace:
<if condition="$show['ipaddress']"><td class="$bgclass"><if condition="$log['ipaddress']"><a href="postings.php?$session[sessionurl]do=getip&ip=$log[ipaddress]">$log[ipaddress]</a><else /> </if></td></if>
with:
<if condition="$show['ipaddress']"><td class="$bgclass"> </td></if>