以Oracle账户登录到数据库，执行以下命令：
1. 进入rman
2. connect target /
3. crosscheck archivelog all;
4. delete expired archivelog all;
5. DELETE ARCHIVELOG ALL COMPLETED BEFORE 'SYSDATE-7';——这个是删除七天前的归档日志
DELETE ARCHIVELOG FROM TIME 'SYSDATE-7'; 删除从7天前到现在的全部日志,慎用
6. crosscheck archivelog all;
7. delete expired archivelog all;
8. 退出：exit