Form2 açılırken Form1 i kapatma

 
      button1_Click(object sender, EventArgs e) 
  { 
     Thread thread = new Thread(new ThreadStart(Form2Show)); 
              thread.SetApartmentState(System.Threading.ApartmentState.STA); 
   
              this.Close(); 
               
              thread.Start(); 
  } 
   
  void Form2Show() 
          { 
   
           Application.Run(new Form2()); 
      
          }