Using PostgreSQL you might want to delete a database or a user you previously created.
To delete a database, you should run the following query.
DROP DATABASE "project";
To delete a user, you should run the following query.
DROP USER "username";
If the user to be deleted is the owner of a database, you're required to change the owner or delete the database, or you will receive the error role "username" cannot be dropped because some objects depend on it.