Flutter 如何删除或隐藏覆盖

我对Flutter 翼和dart 是新手.我想删除覆盖图.我在网上试了很多答案，但还是卡住了.请看我的代码

class MyHomePage extends StatefulWidget {
  const MyHomePage({super.key, required this.title});

  final String title;

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {

void _insertOverlay(BuildContext context) { 
    return Overlay.of(context).insert(
      OverlayEntry(builder: (context) {
        
        
        return Positioned(
          width: MediaQuery.of(context).size.width,
          height: MediaQuery.of(context).size.height,
          top: 0,
          left: 0,
          child: Material(
            color: const Color(0xFF0E3311).withOpacity(0.5),
            child: GestureDetector(
              onTap: (){
                print('OVERLAY ON');
                //on tap, remove or hide the overlay
              },
              child: Container( decoration: BoxDecoration(shape: BoxShape.circle, color: Colors.redAccent), ),
            ),
          ),
        );
      }),
    );
  }

  @override
  Widget build(BuildContext context) {
    
    return Scaffold(
      appBar: AppBar(
       
        title: Text(widget.title),
      ),
      body: Center(
        
        child: Column(
          
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            const Text(
              'Flutter application',
            ),
            Text(
              '',
              style: Theme.of(context).textTheme.headlineMedium,
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: ()=>WidgetsBinding.instance.addPostFrameCallback((_) => _insertOverlay(context)),
        child: const Icon(Icons.add),
      ), // This trailing comma makes auto-formatting nicer for build methods.
    );
  }
}

我已经能够使覆盖显示出来，但我正在try 删除或隐藏它.看看我到目前为止做了什么.我做这件事已经有一段时间了.提前谢谢你