Below version isn’t working due to cross domain issues (As visualforce pages are served from *.force.com domain and salesforce standard pages are served from *.salesforce.com domain, so it results in cross domain errors).

Please read new working version @ http://www.chiragmehta.info/chirag/2010/08/16/salesforce-hide-standard-buttons-display-working-version/

There are many a times where we want to remove few standard buttons from page layout, but there is no such option to remove such restricted buttons. Few such buttons are …

  • “New Note” or “Attach File” button on Google Docs, Notes, & Attachments Related list
  • “Save & Send Invitation” button on New Event page

    • Following is a solution which will hide “Save & Send Invitation” button on New Event page

    STEP1: Visualforce Code

    <apex :page sidebar="false" showHeader="false">
    <script language="javascript" type="text/javascript">
    window.onload = new function()
    {
    window.parent.document.getElementsByName("sendEmail")[0].style.display = 'none';
    window.parent.document.getElementsByName("sendEmail")[1].style.display = 'none';
    }
    </script>

    </apex>

    STEP2: Create a Home Page Component of type (HTML Area)

    <iframe src="/apex/aboveVFPageName" frameborder="0" width="100%" height="100"></iframe>

    STEP3: Add above created Home page component in your home page layout.

    That’s it you are all set, now open New Event and add invitees, automatically the “Save & Send Invitation” button will disappear.