How to untag certain sublevel tags within a document?

try this

#include "glue code.jsx";

var myDoc = app.activeDocument;

var myRuleSet = new Array (new unTag);

with(myDoc){

    var elements = xmlElements;

    __processRuleSet(elements.item(0), myRuleSet);

}

function unTag(){

    this.name = unTag;

    this.xpath = "//Root/*";

    this.apply = function(myElement, myRuleProcessor){

        __processChildren(myRuleProcessor);

        with(myElement){

            try{

                if(myElement.markupTag.name!='products'){

                    alert("ss")

                    myElement.untag();

                    }

                }catch(e){}

            }

        return true;

        }

    }