Remnant files on the disk

Hi,

We took the full backup of my database using RMAN (level 0) followed by "delete obsolete" command.

We still have few remnant files left over in there from last week.Isn't it supposed to delete all these prior files that exist and only save the current full backup files as per the redundancy configurations.

Can some one assist me why there are remnant files even after "delete obsolete" command?

Level 0 backup script:

BACKUP INCREMENTAL LEVEL=0 CUMULATIVE DATABASE;
SQL 'ALTER SYSTEM ARCHIVE LOG CURRENT';
BACKUP ARCHIVELOG ALL;
DELETE OBSOLETE;

My RMAN cofiguration redundancy is 1.

Please help me.