Remove a data type
DROP TYPE [ IF EXISTS ] name [, ...] [ CASCADE | RESTRICT ]
DROP TYPE removes a user-defined data type. Only the owner of a type can remove it.
Do not throw an error if the type does not exist. A notice is issued in this case.
The name (optionally schema-qualified) of the data type to remove.
Automatically drop objects that depend on the type (such as table columns, functions, operators).
Refuse to drop the type if any objects depend on it. This is the default.
To remove the data type box:
DROP TYPE box;
This command is similar to the corresponding command in the SQL standard, apart from the IF EXISTS option, which is a PostgreSQL extension. But note that much of the CREATE TYPE command and the data type extension mechanisms in PostgreSQL differ from the SQL standard.