Merged Incremental Backup not purged the as per retention

@Hello

@Hello,

We have 5.5 TB DB with 12.1 version. We configured the "Merged Incremental Backup" on daily basis. Backup has been running fine on regular basis.

My question backup pieces are not purged after its retention policy. Below is the Rman setting and Backup script. Your suggestion and advice would be more helpful.

RMAN> show all;

using target database control file instead of recovery catalog

RMAN configuration parameters for database with db_unique_name PROD are:

CONFIGURE RETENTION POLICY TO RECOVERY WINDOW OF 7 DAYS;

CONFIGURE BACKUP OPTIMIZATION OFF; # default

CONFIGURE DEFAULT DEVICE TYPE TO DISK; # default

CONFIGURE CONTROLFILE AUTOBACKUP OFF; # default

CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE DISK TO '/nfs_arch_ch0/control_%d_%F';