Code makes box appear after log-in

[Chrisj]

I'm using this web script that works successfully. It has a section where I can add a text box to appear upon a web user log-in. Instead, what I'd like to do is make the log-in box (form) disappear as soon as the user logs-in. Can you tell where(how) I can change this code to accomplish that? Thanks for any help.

 

<br/>
<form action="login.php" method="post" accept-charset="UTF-8" class="middletext">
      <label><font class="font4_15">Username</font></label><span class="username"><input type="text" name="user_name_login" size="9" style="width:70px;" />
  <label><font class="font4_15">Password</font></label><span class="password"><input type="password" name="password_login" size="9" style="width:70px;" />
<input type="submit" value="[var.lang_login_now]" class="btn_vid1" /></a><!--<a href="login.php"></a>-->
<input type="hidden" name="submitted" value="yes" />
<input type="hidden" name="remember_me" value="remember_me" />
</form>
</td></tr></table>

<!--Begin Text Box-->
  <!--<div id="txt-box">-->
  <table id="tabX44">
      				<tbody>
			<tr><td>
  <!--<div class="header-narrow">Text Box</div>-->
  <div class="txt-narrow">

  </div>
  <!--<div class="container-narrow-bottom"></div>-->
  <!--[onload_337;block=div;when [var.show_login_box]!=1;comm]-->
        </td></tr>
  	  				</tbody>
			</table>
  <!--</div>-->
  <!--End Text Box-->