Look for this code or something similier in forumhome template and removing it (it may be in forumhome_forumbit_level1_nopost depending on the style):
HTML Code:
<tr align="center">
<td class="thead"> </td>
<td class="thead" width="100%" align="$stylevar[left]">$vbphrase[forum]</td>
<td class="thead">$vbphrase[last_post]</td>
<td class="thead">$vbphrase[threads]</td>
<td class="thead">$vbphrase[posts]</td>
<if condition="$vboptions['showmoderatorcolumn']">
<td class="thead">$vbphrase[moderator]</td>
</if>
</tr>