If you needed to delete all comments from the start (because I see no comments) I would just disable them. If you don't get that many, I would just check it once or twice a day (bookmark the analytics page). I don't think that Itch.io has time in the near future to make changes on their platform that aren't absolutely necessary. Some people seem to really dislike you or your projects because of the ratings. In the first case I would also disallow the ratings (but I don't know if this affects old reviews, maybe just for the next one). Good luck!