Delete Oracle Database

Since 10g, It is possible to drop a database in Oracle 10g with the new SQL statement drop database.
The command gets rid of datafiles online redo log files, controlfiles and spfile.

shutdown abort;
startup mount exclusive restrict; 
drop database;
exit

Requirements

* database must be closed,
* exclusively mounted,
* restricted


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To delete a database Pre 10g

First:

select  "rm -f "||name from v$controlfile
        union
        select "rm -f "||name from v4datafile
        union
        select "rm -f "||member from v$logfile;

Second:
Clean up above output & make it executable

Third:
If installation follows OFA standard:
remove directory $ORACLE_BASE/admin/$ORACLE_SID

Fourth:
Delete archive log directory (if archive mode)

or)

Depending on if OFA was followed in installation you can use the Oracle Database Configuration Assistant(DBCA). You can create and delete a database with this tool. Delete the database and then remove the files as noted in the previous response.