deleting function from pg_catalog.pg_proc

Hello Folks,

I would like to know if deleting functions from pg_catalog.pg_proc with
the following SQL statement is advisable?

I would like a way of deleting my functions without using the DROP
FUNCTION statement.

------------------------------------------------------------------
delete from pg_catalog.pg_proc where oid in (select sp.oid from
    pg_catalog.pg_proc sp
    inner join pg_namespace ns on sp.pronamespace=ns.oid
where
    ns.nspname='public'
    and sp.proname like 'sys%')
------------------------------------------------------------------
Thank you.