I think you should definitely try, but I don't think it'll work. According to this stackexchange question they could argue that deleting your comments would break the cohesiveness of the discussion and make the available information incomplete.
Art.17, 3a states that the right to be forgotten is not applicable if processing of the data is required to exercise freedom of information. So I don't think posts or comments are affected by the GDPR as long as they don't contain any information that would identify a user
@sensibilidades is probably right that they could just restore the previous state from a backup
In addition to that is a name not necessarily information that would identify you. There are many people out there that share the same name. It would require additional personal information, like address, phone number or something like that
Even if that would help deleting a users Reddit history I wouldn‘t exactly recommend posting putting that information on the internet