If a customer needs to remove an online DSM node in Deep Security, they can follow these steps:

1. Backup the database.
2. Run the following SQL script on the database server to update the manager node to offline using SQL statement:
   UPDATE managernodes SET ShutdownDate = GETDATE(), ShuttingDown = 1 WHERE ManagerNodeID = 1002;
3. Check if the manager node is able to be decommissioned.

By following these steps, the customer should be able to remove the online DSM node that appears twice in the node management.