jqxTreeGrid is a Hierarchical Grid and the returned Data is Hierarchical Array as well. Each record may have sub records stored in its own “records” Array.
And for this reason be default always shows parent and child together. If you want to get flat list, you need to set this array with some custom logic.
Or make some workaround that disable parent with CSS and/or lockRow method, please take a look this example: http://jsfiddle.net/9xunqzra/