[theFM]

go to postbit_legacy template : -

and search for this

PHP Code:

<if condition="$show['quickreply'] AND !$show['threadedmode']">
            <a href="$post[replylink]" rel="nofollow" id="qr_$post[postid]" onclick="return false"><img src="$stylevar[imgdir_button]/quickreply.gif" alt="$vbphrase[quick_reply_to_this_message]" border="0" /></a>
        </if> 


and Just Remove this that will remove the quick reply button
like in
vbulletin.org this button

https://vborg.vbsupport.ru/images/cstyle/blue/buttons/quickreply.gif

Img : -

Thanks.