This would require a modification of the code, you won't be able to change this without access to the files.
Here's the required change anyway:
Find the following code in members.asp (approx. lines 453-455): if mlev = 4 or mlev = 3 then
Response.Write " <td bgcolor=""" & CColor & """ align=""center"" nowrap><font face=""" & strDefaultFontFace & """ size=""" & strDefaultFontSize & """ color=""" & strForumFontColor & """>" & ChkDate(Members_MemberLastHereDate,"",false) & "</font></td>" & vbNewLine
end if
and replace it with the following code: Response.Write " <td bgcolor=""" & CColor & """ align=""center"" nowrap><font face=""" & strDefaultFontFace & """ size=""" & strDefaultFontSize & """ color=""" & strForumFontColor & """>" & ChkDate(Members_MemberLastHereDate,"",false) & "</font></td>" & vbNewLine
(or remove the red code).