De-/activate getfeature-request via button

I have an Openlayers3-map with more than one WMS-Layer. I want to add a button (for every queryable layer) so the user can decide to query the wms-layer or not.

var getfeature = function(click) {
    map.on(click, function (evt) {
        document.getElementById('info').innerHTML = '';
        var viewResolution = (view.getResolution());
        var url = wms_url.getGetFeatureInfoUrl(
            evt.coordinate, viewResolution, projection,
            {
                'INFO_FORMAT': 'text/html'
            });
        if (url) {
            document.getElementById('info').innerHTML =
                '<iframe seamless src="' + url + '"></iframe>';
        }
    });
}

This part works fine so far.

Now combine the getfeature-request with the "user-interface" (here just a checkbox)

var userquery = function() {
    var $input = $( this );
    //checkbox true/false
    if($input.prop("checked")) {
        //change cursor appearance
        map.getViewport().style.cursor = 'help';
        //getfeature-request on singleclick
        getfeature('singleclick');
     } 
    else {
        //change cursor appearance, when checkbox is unchecked
        map.getViewport().style.cursor = '';
        //WHAT TO DO HERE???
        //...
   }
};

the checkbox with id="cursor10"

var checkbox = document.getElementById('cursor10');

and add the functionality via

checkbox.onchange = userquery;

At the moment the getfeature-function is continue working once it's activated.

What do I need to do, so the getfeature function will stop working when the checkbox is unchecked? Or any ideas for another approach?

You can use the unByKey() function to unregister the event listener of the map by its key

see: http://jsfiddle.net/d1wrkb95/2/

var mapEventKey;

var getfeature = function(click) {
    mapEventKey = map.on(click, function (evt) {
        document.getElementById('info').innerHTML = '';
        var viewResolution = (view.getResolution());
        var url = wms_url.getGetFeatureInfoUrl(
            evt.coordinate, viewResolution, projection_to,
            {
                'INFO_FORMAT': 'text/html'
            });
        if (url) {
            document.getElementById('info').innerHTML =
                '<iframe seamless src="' + url + '"></iframe>';
        }
    });
};


var userquery = function() {
    var $input = $( this );
    //checkbox true/false
    if($input.prop("checked")) {
        //cursor ändern
        map.getViewport().style.cursor = 'help';
        //getfeatureabfrage bei einzelklick
        getfeature('singleclick');
     } 
    else {
        map.unByKey(mapEventKey);
        map.getViewport().style.cursor = '';
   }
};