"drop function" vs. "delete from pg_proc"

I'm considering writing some semi-automatic software that would create
and drop functions in a PostgreSQL database. I'm considering whether my
software must use the "drop function" command, or whether it can get
away with issuing "delete from pg_proc" commands. Is it safe to drop
functions by deleting from the pg_proc table?

Many database objects are held in tables (types, classes, functions,
etc). In general, is it safe or advisable to delete from the associated
table, rather than using the "official" drop command? What is the
difference between the two methods?

Thanks,
--- Bob Fischer