无法从 Datagrid C# 中的下拉列表中删除项

public static Dictionary<int, string> GetCategorySubDivisionDesc()
{
    Dictionary<int, string> values = new Dictionary<int, string>();
    values.Add(0, "Please select");
    values.Add(1, "Whole Property Wanted");
    values.Add(2, "Flatshares & Rooms Wanted");
    values.Add(3, "Whole Properties Available To Rent");
    values.Add(4, "Flatshares & Rooms Available To Rent");
    values.Add(5, "Looking for Professional Space to Rent/Share");
    //values.Add(6, "Looking for Professional Space to Share");
    values.Add(7, "Looking for Professional Space to Buy");
    values.Add(8, "Practices Wanted to Buy");           
    return values;
}
Dictionary<int, string> CategorySubDivisionValues = Enums.GetCategorySubDivisionDesc();

我需要在数据网格中使用这些值的下拉列表，因此我_ItemDataBound事件中的每个下拉列表绑定它

DropDownList cboSpaceCategory = (DropDownList)e.Item.FindControl("cboSpaceCategory");
            cboSpaceCategory.DataSource = CategorySubDivisionValues;
            cboSpaceCategory.DataTextField = "Value";
            cboSpaceCategory.DataValueField = "Key";
            cboSpaceCategory.DataBind();
 cboSpaceCategory.Items.Remove("Practices Wanted to Buy"); // not working
 cboSpaceCategory.Items.RemoveAt(int.Parse(cboSpaceCategory.Items.FindByText("Practices Wanted to Buy").Value)); // not working

但是，这不会删除该项目。请建议任何删除项目的方法。