I saw a comment somewhere saying the title and had links but I lost the comment now. One of the links was going to raddle.me which is a Reddit like site
The political views of the main devs are controversial but it doesn’t really matter since Lemmy is free and open source. No one owns or runs it. Only lemmy.ml specifically is run by the devs.
Look at my other comment with the link. It’s saying that even if you delete your account the only thing that happens is that you can’t access it anymore but every comment and data is still in the database
If you don't want it there don't post it. The internet is scraped and copied and backed up. You can ask for it to be deleted but the company likely doesn't own every copy.