How to drop an Oracle database without DBCA

If, when you come to remove an Oracle database, you find that DBCA is not available perhaps due to some installation issue or missing files then do not fret as it is still possible to remove the database by following these steps…
1 – Set the Oracle SID

D:\Oracle\product\11.2.0\dbhome_1\BIN>set ORACLE_SID=TESTDB

2 – Connect to the database and verify the name

D:\Oracle\product\11.2.0\dbhome_1\BIN>sqlplus / as sysdba
SQL*Plus: Release 11.2.0.2.0 Production on Fri Nov 25 09:38:04 2016
Copyright (c) 1982, 2010, Oracle.  All rights reserved.
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.2.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL> select name from v$database;
NAME
---------
TESTDB

3 – Shutdown the database

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

4 – Startup the database in exclusive mode

SQL> startup mount exclusive restrict
ORACLE instance started.
Total System Global Area 2137886720 bytes
Fixed Size                  2254896 bytes
Variable Size            1577060304 bytes
Database Buffers          553648128 bytes
Redo Buffers                4923392 bytes
Database mounted.

5 – Drop the database

SQL> drop database;
Database dropped.
Disconnected from Oracle Database 11g Enterprise Edition Release 11.2.0.2.0 - 64 bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

You can now check that the database has been dropped by checking that the database files have been removed. Check also that the services have been removed, if they are still listed then you can open a DOS prompt with administrator privileges and then use sc delete <service name>.