How to drop oracle database ?

Oracle database drop .. 

SQL> drop database;

drop database

*

ERROR at line 1:

ORA-01586: database must be mounted EXCLUSIVE and not open for this operation

SQL> shutdown immediate ;

Database closed.

Database dismounted.

ORACLE instance shut down.

SQL> startup mount exclusive restrict ;

ORACLE instance started.

Total System Global Area 1068937216 bytes

Fixed Size                  2260088 bytes

Variable Size             671089544 bytes

Database Buffers          390070272 bytes

Redo Buffers                5517312 bytes

Database mounted.

SQL> exit

Disconnected from Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production

With the Partitioning, Automatic Storage Management, OLAP, Data Mining

and Real Application Testing options

[oracle@oraasm12c dbs]$ sqlplus / as sysdba

SQL*Plus: Release 11.2.0.4.0 Production on Sat Jul 1 19:03:25 2017

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, Automatic Storage Management, OLAP, Data Mining

and Real Application Testing options

SQL>  drop database;

Database dropped.

No file in ASM ...

ASMCMD [+DATA] > ls -s

Block_Size  Blocks  Bytes  Space  Name

                                  ASM/

                                  ORA12C/

                                  ORAWIN/

       512      15   7680      0  orapwasm => +DATA/ASM/PASSWORD/pwdasm.256.938381713

                                  vihaan/