如何在flutter中删除google地图中的特定标记？

import 'package:flutter/material.dart';
import 'package:google_maps_flutter/google_maps_flutter.dart';

class MapScreen extends StatefulWidget {
  @override
  _MapScreenState createState() => _MapScreenState();
}

class _MapScreenState extends State<MapScreen> {
  GoogleMapController mapController;
  List<Marker> markers = [];

  void _onMapCreated(GoogleMapController controller) {
    mapController = controller;
  }

  void _addMarker(LatLng position) {
    final marker = Marker(
      markerId: MarkerId(position.toString()),
      position: position,
    );
    markers.add(marker);
    mapController.addMarker(marker);
  }

  void _removeMarker(Marker marker) {
    markers.remove(marker);
    mapController.removeMarker(marker.markerId);
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Google Map'),
      ),
      body: GoogleMap(
        onMapCreated: _onMapCreated,
        initialCameraPosition: CameraPosition(
          target: LatLng(37.42796133580664, -122.085749655962),
          zoom: 10,
        ),
        markers: Set<Marker>.from(markers),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () {
          // 添加一个新标记
          _addMarker(LatLng(37.43296265331129, -122.08832357078792));
        },
        child: Icon(Icons.add),
      ),
    );
  }
}