Unregister a Database from RMAN catalog DB

Connect to RMAN catalog Database:

SQL> conn rman/rman@catlogdb
Connected.


Get the details of a database which need to de-register

SQL> SELECT db_key, dbid, name,RESETLOGS_TIME FROM rc_database where NAME like '%DBNAME%';

    DB_KEY       DBID NAME     RESETLOGS_TIME
---------- ---------- -------- ------------------
   3288657 3228736951 DBNAME 08-MAR-16

 
Execute below to Unregister a database from RMAN catalog DB
   
SQL> EXECUTE dbms_rcvcat.unregisterdatabase(db_key,dbid);

Example:
SQL> EXECUTE dbms_rcvcat.unregisterdatabase(3288657,3228736951);