var wmsLayer2 = new ol.layer.Image({
      source: wmsSource2
    });

    $("#Buildings_chkbx").change(function(){
bool = !bool;
if(bool)
      layers.push("wmsLayer2");
else
//remove layer...
    });


    var map = new ol.Map({
      target: 'map',
      layers: [baseLayer, wmsLayer],
      view: new ol.View({
        center: ol.proj.fromLonLat([33.33386, 35.14710]),
        zoom: 14
      })
    });