How to remove ListView Item using arrayadapter and notifyDataSetChanged

I have ListView in which I am setting ImageView,2 TextView and 2 ImageButton. ImageButtons are for add and remove listItem.
Here is my code...

Helper.java

import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListView;
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.
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import com.example.customObject.ContactBean;
import com.example.helper.HelperAdaptor;
import com.example.helper.ImageHelper;

public class Helper extends Activity implements OnItemClickListener {
    private List<ContactBean> list = new ArrayList<ContactBean>();
    private ListView listView;
    private Button add_helper;
    public HelperAdaptor objAdapter ;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_helper);

        listView = (ListView) findViewById(R.id.lstview_helper_helperlist);
        listView.setOnItemClickListener(this);
        add_helper = (Button) findViewById(R.id.btn_helper_addhelper);
        add_helper.setOnClickListener(new OnClickListener() {           
            @Override
            public void onClick(View v) {
                Intent intent = new Intent(getApplicationContext(),
                        ContactListActivity.class);
                startActivityForResult(intent, SELECT_CONTACT);
            }
        });
    }

    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (resultCode == RESULT_OK) {
            if (requestCode == SELECT_CONTACT) {

                ContactBean objContact = new ContactBean();
                objContact.setName(helperName);
                objContact.setPhoneNo(helperNumber);
                objContact.setPic(image);
                list.add(objContact);
                objAdapter = new HelperAdaptor(Helper.this,
                        R.layout.activity_helper_rows, list);
                listView.setAdapter(objAdapter);

            }
        }
    }

    @Override
    public void onItemClick(AdapterView<?> listview, View v, int position,
            long id) {
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.helper, menu);
        return true;
    }
}

HelperAdapter.java

import android.view.View.OnClickListener;
import android.widget.ArrayAdapter;
import android.widget.ImageButton;
import android.widget.ListView;
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.
.
import com.example.customObject.ContactBean;
import com.example.helpmerestart.ContactListActivity;
import com.example.helpmerestart.R;

public class HelperAdaptor extends ArrayAdapter<ContactBean> {

    private Activity activity;
    private List<ContactBean> items;
    private int row;
    private ContactBean objBean;
    private ViewHolder holder;
    private int itemIndex;
    private View view;

    public HelperAdaptor(Activity act, int row, List<ContactBean> items) {
        super(act, row, items);

        this.activity = act;
        this.row = row;
        this.items = items;

    }

    @Override
    public View getView(final int position, View convertView, ViewGroup parent) {
        view = convertView;
        itemIndex = position;
        if (view == null) {
            LayoutInflater inflater = (LayoutInflater) activity
                    .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            view = inflater.inflate(row, null);

            holder = new ViewHolder();
            view.setTag(holder);
        } else {
            holder = (ViewHolder) view.getTag();
        }

        if ((items == null) || ((position + 1) > items.size()))
            return view;

        objBean = items.get(position);

        holder.add = (ImageButton) view.findViewById(R.id.btn_helper_add);
        holder.remove = (ImageButton) view.findViewById(R.id.btn_helper_remove);

        if (holder.tvname != null && null != objBean.getName()
                && objBean.getName().trim().length() > 0) {
            holder.tvname.setText(Html.fromHtml(objBean.getName()));
        }
        if (holder.tvPhoneNo != null && null != objBean.getPhoneNo()
                && objBean.getPhoneNo().trim().length() > 0) {
            holder.tvPhoneNo.setText(Html.fromHtml(objBean.getPhoneNo()));
        }
        if (holder.profilepic != null && null != objBean.getPic()) {
            holder.profilepic.setImageBitmap(objBean.getPic());
        }

        holder.add.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                addHelper();
            }

        });
        holder.remove.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                items.remove(itemIndex); 
    //trying to call notifyDataSetChanged() here

            }
        }

        );
        return view;
    }

    public void addHelper() {
        Intent intent = new Intent(activity.getApplicationContext(),
                ContactListActivity.class);
        activity.startActivityForResult(intent, SELECT_CONTACT);
        holder.add.setClickable(false);
        holder.remove.setClickable(true);
    }



    public class ViewHolder {
        public TextView tvname, tvPhoneNo;
        public ImageView profilepic;
        public ImageButton add, remove;
    }
}

the problem is I am not able to remove the listItem for which remove button is clicked. you can refer Previous post to understand what exactly I want to have. I am trying to call notdifyDataSetChanged() in onClick() of remove button but not getting how to do that.

Any other method by which I can get my purpose working will be appritiated.
Regards..
Sourabh