DROP DOMAIN name [, ...] [ CASCADE | RESTRICT ]
DROP DOMAIN will remove a domain. Only the owner of a domain can remove it.
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.