Hi, Gamer.

Unless there's some other way that I don't know of, to delete your rating for/of something, you must do it individually from the show's (or movie's) rating star symbol. Click once on that star symbol, to get the row of 5 stars to appear, then click on the "-" (minus) symbol that's at the beginning of the row. That'll eliminate whatever rating you gave that title.

To the best of my knowledge, there's no way to delete, all at once, all t.v. ratings that you've so far given.