To delete an instance using DBCA in interactive mode, perform the following steps:
Start DBCA.
Start DBCA on a node other than the node that hosts the instance that you want to delete. The database and the instance that you plan to delete should be running during this step.
On the DBCA Operations page, select Instance Management and click Next. DBCA displays the Instance Management page.
On the DBCA Instance Management page, select the instance to be deleted, select Delete Instance, and click Next.
On the List of Cluster Databases page, select the Oracle RAC database from which to delete the instance, as follows:
On the List of Cluster Database Instances page, DBCA displays the instances that are associated with the Oracle RAC database that you selected and the status of each instance. Select the cluster database from which you will delete the instance.
Click OK on the Confirmation dialog to proceed to delete the instance.
DBCA displays a progress dialog showing that DBCA is deleting the instance. During this operation, DBCA removes the instance and the instance's Oracle Net configuration.
Click No and exit DBCA or click Yes to perform another operation. If you click Yes, then DBCA displays the Operations page.
Verify that the dropped instance's redo thread has been removed by using SQL*Plus on an existing node to query the GV$LOG view. If the redo thread is not disabled, then disable the thread. For example:
SQL> ALTER DATABASE DISABLE THREAD 2;
Verify that the instance has been removed from OCR by running the following command, where db_unique_name is the database unique name for your Oracle RAC database:
srvctl config database -d db_unique_nameIf you are deleting more than one node, then repeat these steps to delete the instances from all the nodes that you are going to delete.