删除动态控件 :清除有效，但未删除

我最近遇到了一个问题，我在下拉菜单的选择上生成动态控件。当选择更改时，我必须生成另一组动态控件，删除现有控件。

所以我在做以下不起作用的事情：

    private void ClearDynamicControls()
    {
        if (adapter != null)
        {
            //This has all the controls saved in some dictionary, key as control ID
            var controls = adapter.GetAllControls().Keys;
            Control mainControl = (PlaceHolder)this.Form.FindControl("MainContent");
            foreach (String controlName in controls)
            {
                Control controlToRemove = this.Form.FindControl("MainContent").FindControl(controlName);
                mainControl.Controls.Remove(controlToRemove);
            }
            var controls2 = mainControl.Controls;
            //clearing the controls in the dictionary
            adapter.ClearAllControls();
        }

    }

But the similar code with Clear() method is working fine. So what shall I do about it?

    private void ClearDynamicControls()
    {
        if (adapter != null)
        {
            //This has all the controls saved in some dictionary, key as control ID
            var controls = adapter.GetAllControls().Keys;
            Control mainControl = (PlaceHolder)this.Form.FindControl("MainContent");
            mainControl.Controls.Clear();

            //clearing the controls in the dictionary
            adapter.ClearAllControls();
        }

    }

By this code, all the controls(both dynamic and static) are removed. So what shall be done about it?

Please let me know if I am doing something wrong.

I am calling this method on dropdown selection change event firing. These controls are added to the table...

foreach(Control control in Controls){
  if(control.Name == "yourControlName"){
    Controls.Remove(control);
  }
}

foreach(Control control in panel.Controls){      
        panel.Controls.Remove(control);
    }