Follow Below steps to drop a database in oracle.
Shutdown the database
[localhost]$ export ORACLE_SID=DBACLASS [localhost]$ sqlplus / as sysdba SQL*Plus: Release 11.2.0.4.0 Production on Aug 24 15:35:35 2015 Copyright (c) 1982, 2011, Oracle. All rights reserved. SQL> shutdown immediate; Database closed. Database dismounted. ORACLE instance shut down.
Mount the database in exclusive restrict mode
SQL> startup mount exclusive restrict ORACLE instance started. Total System Global Area 217157632 bytes Fixed Size 2211928 bytes Variable Size 159387560 bytes Database Buffers 50331648 bytes Redo Buffers 5226496 bytes Database mounted.
Drop the database
SQL> drop database; Database dropped.