DROP LANGUAGE — remove a procedural language
DROP [ PROCEDURAL ] LANGUAGE [ IF EXISTS ] name [ CASCADE | RESTRICT ]
   DROP LANGUAGE removes the definition of a
   previously registered procedural language.  You must be a superuser
   or the owner of the language to use DROP LANGUAGE.
  
    As of PostgreSQL 9.1, most procedural
    languages have been made into “extensions”, and should
    therefore be removed with DROP EXTENSION
    not DROP LANGUAGE.
   
IF EXISTSDo not throw an error if the language does not exist. A notice is issued in this case.
nameThe name of an existing procedural language.
CASCADEAutomatically drop objects that depend on the language (such as functions in the language), and in turn all objects that depend on those objects (see Section 5.15).
RESTRICTRefuse to drop the language if any objects depend on it. This is the default.
   This command removes the procedural language
   plsample:
DROP LANGUAGE plsample;
   There is no DROP LANGUAGE statement in the SQL
   standard.