DROP [ PROCEDURAL ] LANGUAGE 'name'
DROP PROCEDURAL LANGUAGE will remove the definition of the previously registered procedural language called name.
The DROP PROCEDURAL LANGUAGE statement is a Postgres language extension.
Refer to CREATE LANGUAGE for information on how to create procedural languages.
No checks are made if functions or trigger procedures registered in this language still exist. To re-enable them without having to drop and recreate all the functions, the pg_proc's prolang attribute of the functions must be adjusted to the new object ID of the recreated pg_language entry for the PL.