ngmap with drawingMode circle dont allow user to draw multi circle

[jangholi]

i use drawing-manager my code is like this:

<ng-map zoom="13" center="37.774546, -122.433523"
    map-type-id="ROADMAP"
    street-view-control-options="{position: 'LEFT_CENTER'}">
    <drawing-manager
      on-overlaycomplete="vm.onMapOverlayCompleted()"
      drawing-control-options="{position: 'TOP_CENTER',drawingModes:['polygon','rectangle','circle']}"
      drawingControl="true"
      drawingMode="null"
      markerOptions="{icon:'www.example.com/icon'}"
      rectangleOptions="{fillColor:'red'}"
      circleOptions="{fillColor: '#FFFF00',fillOpacity: 1,strokeWeight: 5,clickable: false,zIndex: 1,editable: true}" >
    </drawing-manager>
  </ng-map>

in this example user can draw multi circle but i want let user draw just one circle... how can i do it?