Sometimes when you try to delete / drop a PostgreSQL database, it doesn’t work. To fix this, you have to drop the database from the command prompt using this command:
dropdb –username=xxx –password=yyy zzz
Where xxx is the username of an account with permission to drop the database, yyy is the password for that user account and zzz is the name of the database you are trying to drop.
You will then be asked to re-enter your password and the database will then drop.
If this doesn’t work, restart the postgresql-x64-9.1 – PostgreSQL Server 9.1 service from the services.msc mmc console, then immediately run the command to drop the database again (before doing anything else).
If this doesn’t work, you will get an error explaining why you can’t drop the database. Typically this is because there’s an active connection to the database.