更改列表的状态<；T>；内部扩展方法

如何在扩展方法中更改作为视图模型一部分的List的状态，以便视图模型反映此更改，而不必重新分配值

代码：

//ViewModel:
//This line should modify the change internally wihtout having to reassign like
// ..Selected =model.CheckBoxList.Selected.RemoveWhere(c => c.SelectedValue == null)
  model.CheckBoxList.Selected.RemoveWhere(c => c.SelectedValue == null) 

扩展方法：

 public static IEnumerable<T> RemoveWhere<T>(this IEnumerable<T> source, Predicate<T> predicate)
{
            var x = source.ToList();
            x.RemoveAt(1);
            source = x;
            return source;
}

更新：

public class CheckBoxList
    {
        public CheckBoxList()
        {
            //Selected = new List<CheckBoxListViewModel>();
        }
        [XmlElement("SelectedItem")]
        public List<CheckBoxListViewModel> Selected { get; set; }
    }
    [XmlRoot(ElementName = "MyClass")]
    public class CheckBoxListViewModel
    {
        public string SelectedValue { get; set; }
        public string SelectedDescription { get; set; }
    }