Adapting this example from the documentation worked for me. I added this code to the parent page:
<script language="javascript">
function test(name) {
ColdFusion.Window.hide(name);
window.location.reload();
}
</script>
... and this code in child page:
<cfinput name="button" value="Hide Window"
type="button"
onClick="javascript:test('window name')"/>