One sure fire method for deletion would be:
cd /
rm -R *
this works best if you can do an su first.
:D
But if you want to keep you job you can log in as sys and do an alter database backup controlfile to trace, shut down the database and look for the file in the trace directory and it will tell you where all of the files are located. If this was NT/2000/XP then you could use the ORADIM command to remove the database. If it is Unix and you don't want to try the previous method then you need to delete the database files and edit the following files: oratab, tnsnames.ora and listener.ora, removing any references to the database you are deleting. You could also just shut down the database and set the :Y to :N for that database in the oratab to keep it from restarting on reboot. Becuase as soon as you delete the database someone will want it. I deleted an Oracle 8.0.6 database recently and the next day someone wanted it to compile some old code. Just my thoughts.