I know genomes. Don't delete your DNA

Yeah, this seems like terrible advice.

Just because DNA currently doesn't say much about you that can theoretically be used against you, that doesn't stop bad actors from using it as a pretense. Don't imagine what an honest person will do with it. Imagine what a dishonest person might try to do with it. Act accordingly.

And what's the opposite side? Where's the benefit of letting them keep it? You can always get your DNA tested again later if they actually come out with a useful application of the information.