RMAN> delete backup;
using channel ORA_DISK_1
List of Backup Pieces
BP Key BS Key Pc# Cp# Status Device Type Piece Name
------- ------- --- --- ----------- ----------- ----------
1 1 1 1 AVAILABLE DISK /tmp/database_backups/07npvr1c_1_1.bak
2 2 1 1 AVAILABLE DISK /tmp/database_backups/08npvr5r_1_1.bak
3 3 1 1 AVAILABLE DISK /tmp/database_backups/09npvr60_1_1.bak
4 4 1 1 AVAILABLE DISK /tmp/database_backups/0anpvr62_1_1.bak
5 5 1 1 AVAILABLE DISK +DATA/primdb/backupset/2012_12_17/nnndf0_tag20121217t113005_0.1094.802265461
6 6 1 1 AVAILABLE DISK +DATA/primdb/autobackup/2012_12_17/s_802265992.1095.802266029
Do you really want to delete the above objects (enter YES or NO)? yes
...Deleting all copies is same as deleting all backups, just replace BACKUP to COPY.
RMAN> delete copy;