Oracle Database how to delete SBT backup record from control file while tape backup not accessible

If your primary goal is to clean up your repository or control file because the physical tape environment is decommissioned. You can permanently remove these expired catalog entries with following steps,

* Allocate maintenance channel with 'dummy' tape device instead of actual physical tape device.

  ALLOCATE CHANNEL FOR MAINTENANCE DEVICE TYPE sbt PARMS 'SBT_LIBRARY=oracle.disksbt, ENV=(BACKUP_DIR=/tmp)';

* Crosscheck tape backup, to mark tape backup as expired because the backup is, for sure, not available in 'dummy' tape device.

CROSSCHECK BACKUP DEVICE TYPE sbt;

* Delete expired backup

DELETE NOPROMPT EXPIRED BACKUP DEVICE TYPE sbt;

* Release maintenance channel

RELEASE CHANNEL;