SQL> drop user EFMIS_87_LK cascade;
drop user EFMIS_87_LK cascade
*
ERROR at line 1:
ORA-00604: error occurred at recursive SQL level 1
ORA-00054: resource busy and acquire with NOWAIT specified or timeout expired

SQL*Plus: Release 11.2.0.4.0 Production on Wed Nov 30 17:03:42 2016

Copyright (c) 1982, 2013, Oracle.  All rights reserved.

Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
With the Partitioning, Real Application Clusters, Automatic Storage Management, OLAP,
Data Mining and Real Application Testing options

SQL> drop user EFMIS_87_LK cascade;
drop user EFMIS_87_LK cascade
*
ERROR at line 1:
ORA-00604: error occurred at recursive SQL level 1
ORA-00054: resource busy and acquire with NOWAIT specified or timeout expired

SQL> exit

重新执行drop user操作即可。