DROP DATABASE name
This message is returned if the command is successful.
You must have the special CREATEDB privilege to drop databases. See CREATE USER.
The template1 database cannot be removed. It's not in your interest.
You cannot be connected to the database your are about to remove. Instead, you could connect to template1 or any other database and run this command again.
This message occurs if the specified database does not exist.
You must be the owner of the database. Being the owner usually means that you created it as well.
You must finish the transaction in progress before you can call this command.
The database was dropped (unless other error messages came up), but the directory where the data is stored could not be removed. You must delete it manually.
DROP DATABASE removes the catalog entries for an existing database and deletes the directory containing the data. It can only be executed by the database owner (usually the user that created it).
This command cannot be executed while connected to the target database. Thus, it might be more convenient to use the shell script dropdb, which is a wrapper around this command, instead.
Refer to CREATE DATABASE for information on how to create a database.