How can I delete the column of the post icons in red here?
In Forum Display Templates >> forumdisplay_thread template remove this:
<td align="center" class="{$bgcolor}{$thread_type_class}" width="2%">{$icon}</td>
In Forum Display Templates >> forumdisplay_threadlist template change:
<td class="tcat" colspan="3" width="66%">
to:
<td class="tcat" colspan="2" width="66%">