Style Manager-> Forum Display Templates-> FORUMHOME
Look for the following code
$vbphrase[threads]: $totalthreads,
$vbphrase[posts]: $totalposts,
$vbphrase[members]: $numbermembers
<if condition="$show['activemembers']">,
<span title="<phrase 1="$vboptions[activememberdays]">$vbphrase[within_the_last_x_days]</phrase>">$vbphrase[active_members]: $activemembers</span>
</if>
The code that is in red either delete it or comment it out with <!-- -->
