Fechar Forms

procedure TForm1.Button2Click(Sender: TObject);
var
 i:Integer;
begin
i:=0;
while i <= Application.ComponentCount-1 do
  begin
    if application.Components[i] is Tform Then
      begin
        showmessage((application.Components[i].name));
          //Form1 = Nome do seu FormPrincipal
          if TForm(application.Components[i]).name <> ´Form1´ Then
            begin
              if (TForm(application.Components[i])).Visible Then
                 begin
                   Showmessage(´Destruindo´);//desnecessário
                   Tform(Application.Components[i]).Hide;
                end;
            end;
     end;
    i:=i+1;
  end;
end;