Changing tables, different number of columns

If I load the grid from a table (CSV) containing four columns, then subsequently reload it with a table containing only two columns, the last two columns from the first table are still visible and contain "undefined". Do the table and grid objects have to be destroyed and recreated, or is there a way to force a new number of columns?

To change the number of columns either you set column count

obj.setColumnProperty("count", 2);

of assign array of column labels

obj.setColumnProperty("texts", ["label1", "label2"]);