DROP TYPE typename [, ...]
DROP TYPE will remove a user type from the system catalogs.
Only the owner of a type can remove it.
DROP TYPE statement is a Postgres language extension.
Refer to CREATE TYPE for information on how to create types.
It is the user's responsibility to remove any operators, functions, aggregates, access methods, subtypes, and tables that use a deleted type.
If a built-in type is removed, the behavior of the backend is unpredictable.