how I can delete a row from a javascript function from a button for example
If you're using a DataView, use the following:
DataView.deleteItem(RowID);//RowID is the actual ID of the row and not the row number
Grid.invalidate();
Grid.render();
If you only know the row number, you can get theRowID using:
var item = DataView.getItem(RowNum);//RowNum is the number of the row
var RowID = item.id