function loadXML()
{
    var bOneway = document.form.oneWay.value;
    var bReturn = document.forms["form"].elements["return"].value;
    var bOpenjaw = document.form.openJaw.value;

    var xmlDoc = new ActiveXObject("MSXML2.DOMDocument.3.0");
    xmlDoc.async="false";

    {
    ==================================    
        removed unnecessary code
    ==================================
    }

    // If the XML document has been completely loaded then proceed 
    if (xmlDoc.readyState==4)
    {
        xmlDoc.loadXML(document.form_dummy.optionXML.value);
        document.form_dummy.optionXML.disabled=true;
        var optNo = parseInt(document.form.optionNumber.value); 
        var optNo_OJ = parseInt(document.form.optionNumber_OJ.value); 
        var iNoOfOpts = parseInt(document.form.iNoOfOpt.value);

        // If the XML document has got options            
        if (xmlDoc.documentElement.hasChildNodes)
        {                
            var oNode_D = xmlDoc.documentElement.selectNodes("Departing").item(0).selectNodes("PiccoOption");
            var oNode_R = xmlDoc.documentElement.selectNodes("Returning").item(0).selectNodes("PiccoOption");                

            var iNoOfDep = parseInt(xmlDoc.documentElement.selectNodes("Departing").item(0).selectNodes("PiccoOption").length);
            var iNoOfRet = parseInt(xmlDoc.documentElement.selectNodes("Returning").item(0).selectNodes("PiccoOption").length);

            // Loop through all the options that have been returned from the database
            for(var i=0; i<iNoOfDep; i++)
            {
                // if the current option is not the option that was selected
                // then go ahead and delete it from the document
                if (i!=optNo)
                {
                    xmlDoc.firstChild.firstChild.selectNodes("Departing").removeChild(oNode_D.item(i));
                }
            }

            // Loop through all the options that have been returned from the database
            for(var i=0; i<iNoOfRet; i++)
            {
                // if the current option is not the option that was selected
                // then go ahead and delete it from the document
                if (i!=optNo_OJ)
                {
                    xmlDoc.firstChild.selectNodes("Returning").removeChild(oNode_R.item(i));
                }
            }
        }
    document.form.optionXML_rev.value=(xmlDoc.xml); // Write the XML to the form field text box to be submitted through to NF2
    }
}

<PiccoReply>
    <Departing>
        <PiccoOption> <-- delete some of these nodes and their childnodes
            ~Other Nodes in here~
        </PiccoOption>
        <PiccoOption> 
            ~Other Nodes in here~
        </PiccoOption>
        <PiccoOption>
            ~Other Nodes in here~
        </PiccoOption>
        <PiccoOption>
            ~Other Nodes in here~
        </PiccoOption>
    </Departing>
    <Returning>
        <PiccoOption> <-- delete some of these nodes and their childnodes
            ~Other Nodes in here~
        </PiccoOption>
        <PiccoOption>
            ~Other Nodes in here~
        </PiccoOption>
        <PiccoOption>
            ~Other Nodes in here~
        </PiccoOption>
        <PiccoOption>
            ~Other Nodes in here~
        </PiccoOption>
    </Returning>
</PiccoReply>