ClearSelection

<div id ="listBox"></div>
<script>
$("#listBox").kendoListBox({
     dataSource: {
        data: [
            { name: "New York" },
            { name: "London" },
            { name: "Paris" }
        ]
    },
    template: "<div>#:name#</div>",
    selectable: true
});
// get a reference to the list box widget
var listBox = $("#listBox").data("kendoListBox");
listBox.clearSelection();
</script>