  
  function loadXMLDoc() {
  
  var xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function() {
    if (this.readyState == 4 && this.status == 200) {
       // Typical action to be performed when the document is ready:
       document.getElementById("demo").innerHTML = xhttp.responseText;
    }
};
xhttp.open("GET", "https://api.thingspeak.com/update?api_key=Y0A92ZT5UMPKK3N1&field1=36&field2=255&field3=250&field4=254&field5=0&field6=3600&field7=0&field8=9", true);
xhttp.send();
    
  }
    function loadXMLDocOff() {
  
  var xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function() {
    if (this.readyState == 4 && this.status == 200) {
       // Typical action to be performed when the document is ready:
       document.getElementById("demo").innerHTML = xhttp.responseText;
    }
};
    xhttp.open("GET", "https://api.thingspeak.com/update?api_key=Y0A92ZT5UMPKK3N1&field1=0&field2=0&field3=0&field4=20&field5=0&field6=3600&field7=0&field8=9", true);
xhttp.send(); 
    
  }
</script>

with this very simple html section

<html>
<head>
  <!--   
  NOTE: This plugin will not be visible on public views of a channel. 
        If you intend to make your channel public, consider using the
        MATLAB Visualization App to create your visualizations.
  -->  
</head>
<body>
  <div id="demo"></div>
<div id="button"><button type="button" onclick="loadXMLDoc()">Lights On</button>
  
</div>
  <div id="offbutton"><button type="button" onclick="loadXMLDocOff()">Lights Off</button>
  
</div>
</body>
</html>