"Hill Street Blues" and Joyce Davenport will be without Capt. Frank Furillo next year, if the NBC series airs at all. "Seven years are enough," series star Daniel J. Travanti said Tuesday, announcing his departure from the six-year-old show. "I have to go act, be free. I don't know how that feels." Travanti made his announcement in the midst of filming the last episode of this season, with no word yet from NBC on whether "Hill Street" will air next year.