If on your social network someone wants his posts to be removed, you have to comply under GDPR, or else. HN for example doesn’t allow to remove your comments after some time.

And how is me deleting my content your service violating your right to free speech exactly?

If it's a part of conversation - like most of social media posts -, I would assume it's fair use to keep it. Like if I interview you, and I publish the video, you can't retract what you said. Why social medias should be different?