Hide the NEW button on Opportunity - Sub Opportunities Related Info tab

First, I don't know java script but have read through some of the documentation.  We do have logic in place through a Global Web Applet to hide two other buttons.  While I've read it can be done other ways since R24, this works so I simply wanted to add the logic to this web applet.  I need to hide the NEW button on the Sub Opportunities related info tab.  Here is my code but it isn't working.  I am guessing I need the id (AXHA-xxxx) for the button.

HTML Head Additions:

<script>

function hideDivsFour(titleBarId, bodyId)

{

  var hiddenDiv = document.getElementById(titleBarId);