In the case of hackernews it seems like email address, ip, profiles, and comments could contain personally identifiable data.
You aren't required to put anything in the profile. If you choose to put information in the profile, you can remove it yourself at any time you so choose.
The GDPR also requires personal information be removed from backups, or at least after a backup is restored (eg: restoring from backup does not negate the original Right To Be Forgotten request).
So while you can remove some of that info yourself, I don't think that can be seen as fulfilling GDPR requirements.
Disclaimer: I am neither a lawyer nor GDPR expert.
You aren't required to put anything in the profile. If you choose to put information in the profile, you can remove it yourself at any time you so choose.