Hi Barry,
Thank you for your interest in Syncfusion Products.
The nested tables can be turned off by removing the relation between child table relation and parent table. Please refer the sample below which illustartes your requirement.
http://files.syncfusion.com/support/GGC.Web/7.103.0.21/F79976/main.htmPlease let me know if this helps you.
Thanks,
Rekha