ORACLE - Drop database

How to drop database with ASM file system ?

SQL> select name from v$database;
NAME
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ATEST
SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup restrict mount
ORACLE instance started.
Total System Global Area 1043886080 bytes
Fixed Size                  2234960 bytes
Variable Size             805307824 bytes
Database Buffers          230686720 bytes
Redo Buffers                5656576 bytes
Database mounted.

SQL> drop database;
Database dropped.