Replace RSS Feed with my own (for real)

Hai guys, so i’ve my own rss-feed generated with Feeder (a mac app) on my main domain.

WordPress is on a subdomain.

I replaced the text in the header.php to use my own rssurl – which works fine – but now I noticed you can access the wordpress-generated feed via /feed /atom etc.

How do I _replace_ the feed or at least disable the wp-one?

Many thanks up front!