myscript.js

function getElementByXpath(path) {
  return document.evaluate(path, document, null, XPathResult.FIRST_ORDERED_NODE_TYPE, null).singleNodeValue;
}

// Checking page title
if (document.title.indexOf("Tracer") != -1) {
    //Creating Elements
    var btn = document.createElement("button");
    var buttonLeft = document.createElement('span');
    buttonLeft.setAttribute('class', 'buttonLeft');

	var buttonText = document.createElement('span');
	buttonText.setAttribute('class', 'buttonText');
    var t = document.createTextNode("Deselect Pega");
    buttonText.appendChild(t);

	var buttonMiddle = document.createElement('span');
	buttonMiddle.setAttribute('class', 'buttonMiddle');
	buttonMiddle.appendChild(buttonText);

	var buttonRight = document.createElement('span');
	buttonRight.setAttribute('class', 'buttonRight');

    btn.type = "button";
    btn.title = "Deselect Pega"
    btn.appendChild(buttonLeft)
    btn.appendChild(buttonMiddle)
    btn.appendChild(buttonRight)

    btn.onclick = function() {
    	var ruleSetList = getElementByXpath("//*[@id=\"RuleSetDisplay\"]/table/tbody/tr/td/table/tbody/tr/td/table/tbody").rows;
    	for (var i = ruleSetList.length - 2; i >= 0; i--) {
    		var ruleSetName = ruleSetList[i].cells[0].innerText.trim();
    		if (ruleSetName.startsWith("Pega-")){
				try{
					ruleSetList[i].cells[1].lastChild.checked = false;
				}	catch (e){
					ruleSetList[i].cells[0].firstChild.checked = false;
				}
    		};
    	}
    };
    //Appending to DOM 
    document.getElementById("RuleSetDisplay").children[0].appendChild(btn);
}