c# MetroFrameWork如何关闭MetroForm

你好，我正在使用metroframework UI使用这个库，但我不能关闭一个窗口this . close ();不适合我，这是一个登录形式后MySQL选择查询得到一个结果，它将打开另一个winform(主)，然后我想关闭登录形式。我的代码在

下面

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using MySql.Data.MySqlClient;
using MetroFramework;
using MetroFramework.Forms;

namespace UI
{
    public partial class Form1 : MetroForm

    {
        public static string SetFname = "";
        public static string Setlname = "";
        public Form1()
        {
            InitializeComponent();
        }
        private void metroButton1_Click(object sender, EventArgs e)
        {

            try
            {
                string MyConnection2 = "Server=localhost;Database=Blue;Uid=root;Pwd=test123;";
                //Display query  
                string Query = "select * from blue.members WHERE user_name = '" + this.metroTextBox1.Text + "' AND  user_pass = '" + this.metroTextBox2.Text + "' AND status = 'Activated'";
                MySqlConnection MyConn2 = new MySqlConnection(MyConnection2);
                MySqlCommand MyCommand2 = new MySqlCommand(Query, MyConn2);
                //  MyConn2.Open();  
                //For offline connection we weill use  MySqlDataAdapter class.  
                MySqlDataReader myReader;
                MyConn2.Open();
                myReader = MyCommand2.ExecuteReader();


                int count = 0;
                while (myReader.Read())
                {
                    count = count + 1;

                }
                if (count == 1)
                {

                    string fname = myReader.GetString("firstname");
                    string lname = myReader.GetString("lastname");

                    MetroMessageBox.Show(this, "Log in Success! Welcome, " + fname + " " + lname + "", "Information", MessageBoxButtons.OK, MessageBoxIcon.Question);

                    Datarecords AddNew = new Datarecords();
                    AddNew.ShowDialog();
                    AddNew.TopMost = true;
                    this.Close();
                }
                else
                {
                    MetroMessageBox.Show(this, "Wrong Username & Password.", "Login Failed", MessageBoxButtons.OKCancel, MessageBoxIcon.Stop);
                    MyConn2.Close();
                }

            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }  

        }
    }
}