TO NOT CLUSTER Option

The TO NOT CLUSTER option drops the cluster attribute on the specified index without affecting the physical order of rows in the table.

Because no more than one clustered index can exist on a given table, you must use the TO NOT CLUSTER option to release the cluster attribute from one index before you assign it to another index on the same table.

Example of dropping the clustering attribute

The following statements illustrate how to remove clustering from one index and how a second index physically reclusters the table: 
CREATE UNIQUE INDEX ix_ord ON orders (order_num);

CREATE CLUSTER INDEX ix_cust ON orders (customer_num); 
. . .
ALTER INDEX ix_cust TO NOT CLUSTER; 
 
ALTER INDEX ix_ord TO CLUSTER;

The first two statements create indexes for the orders table and cluster the physical table in ascending order on the customer_num column. The last two statements recluster the physical table in ascending order on the order_num column.