//删除窗体方法

        private void CloseFrm()

        {

            foreach (Control item in panel1.Controls)

            {

                if (item is Form)  //判断此控件是否是窗体

                {

                    Form objform = (Form)item;

                    objform.Close();  //关闭窗体

                    this.panel1.Controls.Remove(item); //在pannel1中删除这个窗体

                }

            }