此为11g的bug，需要在delete后加上force关键字，如下：
RMAN-08137 When deleting archivelogs even when Streams CAPTURE does not require them [ID 1079953.1]
In this Document
Symptoms
Changes
Cause
Solution
References
Symptoms
Applies To: 11gR1-11gR2
RMAN is unable to delete archive logs from database even though they are not needed by CAPTURE process anymore.
Changes
Cause
In 11g, RMAN looks at MIN_REQUIRED_CAPTURE_CHANGE# in v$database and not at DBA_CAPTURE. By default this value is updated every 6 hours. So by default the value in v$database will be six hours behind the current value.
Solution
Since changing frequency of update to MIN_REQUIRED_CAPTURE_CHANGE# in v$database can not be controlled, following workaround can be used:
Archive log which are not needed by capture process can be deleted using:
delete noprompt force archivelog all completed before 'sysdate-10/1440';
