Stream<QuerySnapshot<Map<String, dynamic>>> myStream = FirebaseFirestore.instance.collection("handleCountM").limit(1).snapshots();

late StreamSubscription<QuerySnapshot<Map<String, dynamic>>> streamSubscription;
  

void handleDelete() {
    streamSubscription = myStream.listen((value) {
      value.docs.forEach((element) {
        element.reference.delete();
      });
    });
  }

  @override
  void dispose() {
    streamSubscription.cancel(); //Cancel your subscription here.
    super.dispose();
  }

你的另一个选择，将是使用一个streambuilder，它会处理订阅和终止为您。
或者你可以用这个

late CollectionReference reference;
  late StreamSubscription streamSubscription;
  @override
  void initState() {
    // TODO: implement initState
    reference = _firestore.collection(singleAuction.id.toString());
    streamSubscription = reference.snapshots().listen((querySnapshot) {
      for (var element in querySnapshot.docChanges) {}
    });
        super.initState();

  }

  @override
  void dispose() {
    // TODO: implement dispose
    super.dispose();
   streamSubscription.cancel();
  }