The MVC Wrappers generate a DataSource that uses server operations
by default, meaning that the aggregates are calculated on the server, so even if you clear the Grid's data the aggregates will not change until the data is synchronized. In the current scenario I would recommend disabling the server operations. Once you do that the aggregates will be calculated client-side, so if you set the data to an empty array then the total will become zero.
Join us on our journey to create the world's most complete HTML 5 UI Framework - download Kendo UI