Removing polygon from google maps drawingManager V3
===

I have a user editable google map where users can draw an overlay polygon onto the map using the drawing manager. This works fine and the console logs the lat lngs I need. However, I need to add a button that will clear the map of the polygon so they can draw again if a mistake was made.. My implementation code is pasted below:

    geocoder = new google.maps.Geocoder();
          var latlng = new google.maps.LatLng(<?php echo $latitude ?>, <?php echo $longitude ?>);
           var myOptions = {
             zoom: <?php echo $zoomlevel ?>,
             center: latlng,
             mapTypeId: google.maps.MapTypeId.ROADMAP
           };
           var map = new google.maps.Map(document.getElementById("map_canvas"), myOptions);

           marker = new google.maps.Marker({
             map:map,
             draggable:true,
             animation: google.maps.Animation.DROP,
             position: latlng
           })

           pos = marker.position;
           //alert(pos);
           document.getElementById("gpsite-surgery-latitude").value = pos.lat();
           document.getElementById("gpsite-surgery-longitude").value = pos.lng();
           
           google.maps.event.addListener(marker, "dragend", function() {
                   var myLatLng = marker.latLng;
                  
                   pos = marker.position;
                   //alert(pos);
                   document.getElementById("gpsite-surgery-latitude").value = pos.lat();
                   document.getElementById("gpsite-surgery-longitude").value = pos.lng();
           })
           
           google.maps.event.addListener(map, 'zoom_changed', function() {
              document.getElementById("gpsite-surgery-zoomlevel").value = map.getZoom();
           });
           
           var drawingManager = new google.maps.drawing.DrawingManager({
            drawingMode: google.maps.drawing.OverlayType.MARKER,
            drawingControl: true,
            drawingControlOptions: {
                position: google.maps.ControlPosition.TOP_CENTER,
                drawingModes: [google.maps.drawing.OverlayType.POLYGON]
            },
            polygonOptions: {
                fillColor: '#ffff00',
                fillOpacity: 0.4,
                strokeWeight: 3,
                clickable: true,
                zIndex: 1,
                editable: false
            }
           });
           

           google.maps.event.addListener(drawingManager, 'polygoncomplete', function (polygon) {
                var coordinates = (polygon.getPath().getArray());
                console.log(coordinates);
            });

           drawingManager.setMap(map);

       });

There is also a marker on the map, you can ignore this.

Thanks in advance