Since you are not keeping Archive around very long the database might be holding the lock on the archivelog file you are trying to delete.That wouldn't be the case. Once an Archivelog has been created, the database doesn't "hold a lock on it". Furthermore, RMAN will not backup an Archivelog that hasn't been completed (i.e. is still in the progress of being written out). Then, the DELETE INPUT will only delete an Archivelog that has been backed up.