If Barbra Streisand cannot delete her name from her house on the Internet, you cannot delete your comments. The Internet only forgets when you don’t want it to. If you want it to forget, it never will.

Posting a comment on the Internet is something that can never be undone. Once it’s out there, it’s out there forever. You can try and delete it, and you might make some progress, you might even be successful, but there are no guarantees, and the more you want it to be deleted the less likely you’ll be able to pull it off.

In a practical sense, just use to built-in features to delete your account and posts. It’s not perfect or guaranteed, but it’s the best you’re going to get.