How to remove space between widgets in Column in flutter?

That's because you are using Flexible and it expands the Widget inside to fill the available space.

Change this :

   body: Column(
          children: <Widget>[
            Flexible(
              flex: 1,

To this:

   body: Column(
          children: <Widget>[
            SizedBox(
              height: 60.0,

And it should work

I see the problem isn't in the Column widget, it's in the first child of it, it takes longer height than you expect, I recommend to use Widget inspector for diagnosing layout issues in the future.

Here is the fix:

1- No need here for the widget, just remove it.

Flexible(
        flex: 1, ...)

2- Set proper dimensions to your avatar image by wrapping it in a Container like this:

Container(
  width: 50,
  height: 50,
  child: ClipOval(clipper: CircleClipper(), child: Image.asset('assets/irene.jpg')),
)

Finally, here is the updated full code:

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

    void main() {
      SystemChrome.setEnabledSystemUIOverlays([]);
      runApp(MyApp());
    }

    class MyApp extends StatelessWidget {
      @override
      Widget build(BuildContext context) {
        return MaterialApp(
          title: 'Flutter Clock',
          theme: ThemeData(primaryColor: Colors.blue),
          home: Social(),
          debugShowCheckedModeBanner: false,
        );
      }
    }

    class Social extends StatelessWidget {
      @override
      Widget build(BuildContext context) {
        return Scaffold(
          appBar: AppBar(backgroundColor: Colors.white, elevation: 0.0),
          backgroundColor: Colors.white,
          body: Column(
            children: <Widget>[
              Row(
                children: <Widget>[
                  Container(
                    width: 50,
                    height: 50,
                    child: ClipOval(clipper: CircleClipper(), child: Image.asset('assets/irene.jpg')),
                  ),
                  Expanded(
                    child: Padding(
                      padding: const EdgeInsets.only(left: 8.0),
                      child: Column(
                        mainAxisAlignment: MainAxisAlignment.start,
                        children: <Widget>[
                          Align(
                              alignment: Alignment.centerLeft,
                              child: Text('Irene',
                                  style: TextStyle(color: Colors.blue, fontWeight: FontWeight.bold, fontSize: 15.0))),
                          Align(alignment: Alignment.centerLeft, child: Text('Yesterday, Ney York'))
                        ],
                      ),
                    ),
                  ),
                  Align(
                    alignment: Alignment.topRight,
                    child: IconButton(
                      color: Theme.of(context).primaryColor,
                      icon: Icon(Icons.menu),
                      onPressed: () {},
                    ),
                  )
                ],
              ),
              Container(
                width: MediaQuery.of(context).size.width / 1.1,
                height: MediaQuery.of(context).size.height / 2,
                child: Card(
                  child: Image.asset('assets/irene.jpg'),
                  color: Colors.white,
                  shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(30.0)),
                  elevation: 10.0,
                ),
              ),
              Padding(
                padding: const EdgeInsets.only(left: 30.0, right: 30.0, top: 15.0),
                child: Row(
                  children: <Widget>[
                    Icon(Icons.thumb_up, color: Colors.black),
                    SizedBox(
                      width: 20.0,
                    ),
                    Icon(Icons.chat, color: Colors.black),
                    Expanded(child: Container()),
                    Icon(Icons.share, color: Colors.black),
                  ],
                ),
              ),
              Expanded(child: Container()),
            ],
          ),
        );
      }
    }