Delete a database on Windows

• Check where the ORACLE_HOME for this instance is:

Start:Run... services.msc
Double click on OracleService<SID>, the first part of "Path to executable" is the home
or
regedit and go to HKEY_LOCAL_MACHINE\SOFTWARE\ORACLE

List of homes and their instances can be seen here.

• Find location of files to delete:

Connect as sys and:

select name from v$datafile;
select member from v$logfile;
show parameter control
show parameter dump
show parameter archive_dest

• Stop the services related to the instance:

set ORACLE_HOME=<oracle home>
oradim -delete -sid <SID>

• Clean up database files:

delete %ORACLE_HOME%\database\PWD<SID>.ora and any pfile, spfile and .dat files
Delete the files and directories shown by above queries

• Check in Registry to make sure entries have gone from HKEY_LOCAL_MACHINE\SOFTWARE\ORACLE\KEY_<home>