Message Oracle RMAN-06091 - no channel allocated for maintenance (of an appropriate type)

ERRORno channel allocated for maintenance (of an appropriate type)
CAUSEA command was entered that requires a maintenance channel, and no maintenance channel is allocated, or none of the appropriate type.
ACTIONUse ALLOCATE CHANNEL FOR MAINTENANCE before deleting backup pieces, or using the CROSSCHECK or DELETE EXPIRED commands. Proxy copies require a non-DISK channel.