The following script allows you to hide markers for a series (Last Tested: v7.0.1.11006)
// Set markers enabled to false for a series
function setMarker(array, enabledFlag) {
for ( var i = 0; i < array.length; i++) {
array[i].marker.enabled = false;
}
}
widget.on('render', function(sender,se){
// edit index of series to select the series you want to turn off markers for
var series = 1;
setMarker(sender.queryResult.series[series].data, false);
})