C#如何释放为控件动态注册的事件

Question

在FORMS的界面上有两个按钮(添加事件，注销事件)，一个文本框。

注册事件类：

class MoveAll
    {
         int x = 0;
        int y = 0;
        bool isDown = false;
        Control controls;
        public MoveAll(Control control)
        {
            controls = control;
            control.MouseDown += new MouseEventHandler(control_MouseDown);
            control.MouseUp += new MouseEventHandler(control_MouseUp);
            control.MouseMove += new MouseEventHandler(control_MouseMove);
        }

        void control_MouseMove(object sender, MouseEventArgs e)
        {
            this.controls.Cursor = Cursors.SizeAll;
            if (isDown)
            {
                controls.Location = new Point(controls.Left + e.X - x, controls.Top + e.Y - y);
            }
        }

        void control_MouseUp(object sender, MouseEventArgs e)
        {
            isDown = false;
        }

        void control_MouseDown(object sender, MouseEventArgs e)
        {
            x = e.X;
            y = e.Y;
            isDown = true;
        }
    }

点击添加按钮，事件为：MoveAll all=new MoveAll(this.TextBox1);

这样，文本框就可以直接在界面上移动。

但是，如果我想释放可以移动文本框的事件，请问，在注销事件的按钮里面应该怎么写？