--Below generates sql to delete functions in a particular schema
SELECT 'DROP FUNCTION ' || quote_ident(ns.nspname) || '.' || quote_ident(proname) || '(' || oidvectortypes(proargtypes) || ');'
FROM pg_proc INNER JOIN pg_namespace ns ON (pg_proc.pronamespace = ns.oid)
WHERE ns.nspname = 'my_messed_up_schema'  order by proname;

Delete many functions

SQL