Drop Oracle DB by sqlplus

- Shutdown Database and start Database on mount Mode.

$ export ORACLE_SID=testdb
$ sqlplus / as sysdba

SQL*Plus: Release 11.1.0.6.0 - Production on Thu Apr 3 13:47:16 2008

Copyright (c) 1982, 2007, Oracle. All rights reserved.


Connected to:
Oracle Database 11g Enterprise Edition Release 11.1.0.6.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

SQL> shutdown;
Database closed.
Database dismounted.
ORACLE instance shut down.

SQL>
SQL> startup mount;
ORACLE instance started.

Total System Global Area 1703624704 bytes
Fixed Size 2145064 bytes
Variable Size 1291846872 bytes
Database Buffers 402653184 bytes
Redo Buffers 6979584 bytes
Database mounted.

- Alter database to restricted session Mode and drop Database.

SQL> alter system enable restricted session;

System altered.

SQL> drop database;

Database dropped.

Disconnected from Oracle Database 11g Enterprise Edition Release 11.1.0.6.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL>

Enjoy!