Data Protection for Oracle uses the Tivoli® Storage Manager backup repository. Each database backup creates an object with a unique name. Since these objects have unique names, they always remain active and never expire. The database administrator (DBA) can control and coordinate copies that are removed from the Tivoli Storage Manager server with RMAN.
Ensure that backdelete=yes is specified by the Tivoli Storage Manager administrator during registration of your node. Specifying this parameter gives you permissions to delete backup objects.