Unregister Database from Catalog When Database is Already Deleted

The following steps can help unregister database when database is already deleted.

1. Connect to catalog database in SQL*Plus using the user having the catalog schema and find out what databases are in there.

SQL> SELECT db_id FROM db;

2. Connect to catalog database in RMAN using the user having the catalog schema and unregister the database.

$ RMAN CATALOG user/pwd@catalog

If you know which dbid is the database you want to unregister, using this command:

RMAN> RUN {
2> SET DBID 1334531173;
3> UNREGISTER DATABASE;
4> }

If you are not sure which dbid, you can try all the dbid is 'db' table in the first step and RMAN will show you database name and ask you if you want to unregister the database.