If you have an environment in which you have to constantly delete databases, or even if you just want to decommission one Database, the most secure way to remove the corresponding files instead of using the rm command is to use the RMAN command DROP DATABASE
If you are using a RAC environment, the first thing you have to do is set the cluster_database parameter to FALSE, once you have done that, shutdown the database
Now that you have shutdown your Database,make sure you have the correct environment variable set, you don’t want to drop a wrong database, and then we will open it in MOUNT mode and set a restricted session
The only thing pending after this, is to drop the database, I don’t like to do it with the NOPROMPT option, as this will be your last chance to repente before doing dropping it.
Update : A great reminder and precaution given by Leighton Nelson ( TW : @leight0nn) is to do a backup … keep just as a safe guard before doing any of theses steps