Remove a domain
DROP DOMAIN [ IF EXISTS ] name [, ...] [ CASCADE | RESTRICT ]
DROP DOMAIN removes a domain. Only the owner of a domain can remove it.
Do not throw an error if the domain does not exist. A notice is issued in this case.
The name (optionally schema-qualified) of an existing domain.
Automatically drop objects that depend on the domain (such as table columns).
Refuse to drop the domain if any objects depend on it. This is the default.
To remove the domain box:
DROP DOMAIN box;
This command conforms to the SQL standard, except for the IF EXISTS option, which is a PostgreSQL extension.