Cannot kill autovacuum

When I set up a database with tons of data I forgot to check in the
.conf file that autovacuum was on.

Now it seems that the stat collection has prepared some tasks to be
done for autovacuum - from my experience I can tell that this will
take weeks or even months.

I disabled autovacuum in the conf file, shut down the database,
restarted it but the autovacuum process is comming up again and
again. If I kill the process it takes just some minutes to start
again to do it's jobs it has in memory.

So, my question should be quite simple - how do I shut down
autovacuum finally to not do anything more on this tables - I hope
the answer is also as simple, but until right now I didn't find any
solution for that.

I'm using 8.2.5 version.