If you use 23andMe, and request data deletion, they will do a best effort to delete the data. It's part of their GDPR requirement. When I was there, I worked on this project and they put a lot of effort into it. A big chunk of engineering org focused GDPR compliance for a month or two. They definitely don't intentionally keep data around if you request deletion.
The one caveat is that data deletion is hard, and its possible that some gets accidentally retained. I left the company over 5 years ago, so I don't know how good their deletion process is now.
One final note: to keep costs low, 23andMe doesn't look at your whole genome. They only look at a handful of "SNPs" in your genome that are known to be significant. If you've heard how we share 99.5% of our DNA with chimpanzees, this is what they're basing this on. They look at the <0.5% of DNA that commonly varies between humans.
The reason I mention this is that, if you're very interested in your DNA sequencing, you may want to opt for a higher cost service that does full genome analysis. I don't know any names but I believe there are some DNA services that do this.