Go into forum.asp and look through the code for where it is displayed, comment out those columns and cross your fingers that you don't mess other things up lol.
I'm using a fairly heavily modified forum so my line numbers may be different from yours, but check these ares:
Line 433 and 434
" <td align=""center"" bgcolor=""" & strHeadCellColor & """><b><font face=""" & strDefaultFontFace & """ size=""" & strDefaultFontSize & """ color=""" & strHeadFontColor & """>Author</font></b></td>" & vbNewLine & _
" <td align=""center"" bgcolor=""" & strHeadCellColor & """><b><font face=""" & strDefaultFontFace & """ size=""" & strDefaultFontSize & """ color=""" & strHeadFontColor & """>Replies</font></b></td>" & vbNewLine & _
Line 582 and 583:
" <td valign=""middle"" align=""center""><font face=""" & strDefaultFontFace & """ size=""" & strDefaultFontSize & """ color=""" & strForumFontColor & """><span class=""spnMessageText"">" & profileLink(chkString(Topic_MName,"display"),Topic_Author) & "</span></font></td>" & vbNewLine & _
" <td valign=""middle"" align=""center""><font face=""" & strDefaultFontFace & """ size=""" & strDefaultFontSize & """ color=""" & strForumFontColor & """>" & Topic_Replies & "</font></td>" & vbNewLine & _
You could get rid of last author and other stuff in a similar way, just look through the code, if you aren't very experienced with asp, get araneae (google search for it) it's a freeware text editor that works excellently, and to a find for the code that I pasted then add a ' mark before the line and save it and upload and you should be set.
ALSO VERY IMPORTANT, BACKUP BACKUP BACKUP its very easy to mess up one of these files, and sometimes not very easy to track the changes you made.
Good Luck