Hi Jerry ,
The Points on the Histogram chart, is an expected behavior. There is no inbuilt function to remove the points on the series column in the Histogram chart. As a work around you can create a combination of Column and SPLine chart to display the Histogram chart.
Here is the sample.
http://websamples.syncfusion.com/samples/Chart.Windows/F74400/main.htmPlease refer to it and let me know if this helps.
Regards,
Nagaraj