XML таблица. Как удалить узлы (группы) дерева, не имеющие подчиненных листов

CREATE TABLE [dbo].[Entity] (
	[EntID] [int] NOT NULL ,
	[EntPrntID] [int] NOT NULL ,
	[EntType] [int] NOT NULL 
) ON [PRIMARY]


INSERT INTO Entity (EntID, EntPrntID, EntType) VALUES(0, 0, 1)
INSERT INTO Entity (EntID, EntPrntID, EntType) VALUES(1, 0, 1)
INSERT INTO Entity (EntID, EntPrntID, EntType) VALUES(2, 0, 1)
INSERT INTO Entity (EntID, EntPrntID, EntType) VALUES(3, 1, 2)
INSERT INTO Entity (EntID, EntPrntID, EntType) VALUES(4, 1, 2)

DELETE Entity
FROM Entity e INNER JOIN
WHERE e.EntID IN  
	(
	SELECT DISTINCT ePrnt.EntID
	FROM Entity ePrnt LEFT JOIN Entity eCld ON ePrnt.EntID = eCld.EntPrntID
	WHERE ePrnt.EntType = 1 AND eCld.EntID IS NULL
	) AS eEmpty ON e.EntID = eEmpty.EntID

    Public Sub FillXMLEntity()
    	'Заполнить таблицу
        Dim ds As New DataSet
        Dim dt As New DataTable("Entity")
        Dim dColEntID As New DataColumn("EntID")
        Dim dColEntPrntID As New DataColumn("EntPrntID")
        Dim dColEntType As New DataColumn("EntType")
        Dim dr As DataRow
        Dim sPathXML As String = Path.Combine(Application.StartupPath, "Entity.XML")

        With dColEntID
            .DataType = System.Type.GetType("System.Int32")
            .AllowDBNull = False
            .Unique = True
            .ReadOnly = True
            .Caption = "EntID"
            .ColumnName = "EntID"
        End With 'dColID

        With dColEntPrntID
            .DataType = Type.GetType("System.Int32")
            .AllowDBNull = False
            .ReadOnly = True
            .Caption = "EntPrntID"
            .ColumnName = "EntPrntID"
        End With 'dColEntPrntID

        With dColEntType
            .DataType = Type.GetType("System.Int32")
            .AllowDBNull = False
            .ReadOnly = True
            .Caption = "EntType"
            .ColumnName = "EntType"
        End With 'dColEntType

        dt.Columns.Add(dColEntID)
        dt.Columns.Add(dColEntPrntID)
        dt.Columns.Add(dColEntType)

         dr = dt.NewRow
        dr("EntID") = 0
        dr("EntPrntID") = 0 'корень ссылается сам на себя
        dr("EntType") = 1
        dt.Rows.Add(dr)
        dt.AcceptChanges()

        dr = dt.NewRow
        dr("EntID") = 1
        dr("EntPrntID") = 0
        dr("EntType") = 1
        dt.Rows.Add(dr)
        dt.AcceptChanges()

        dr = dt.NewRow
        dr("EntID") = 2
        dr("EntPrntID") = 0
        dr("EntType") = 1
        dt.Rows.Add(dr)
        dt.AcceptChanges()

        dr = dt.NewRow
        dr("EntID") = 3
        dr("EntPrntID") = 1
        dr("EntType") = 2
        dt.Rows.Add(dr)
        dt.AcceptChanges()

        dr = dt.NewRow
        dr("EntID") = 4
        dr("EntPrntID") = 1
        dr("EntType") = 2
        dt.Rows.Add(dr)
        dt.AcceptChanges()
        ds.Tables.Add(dt)
        If DeleteFilePC(aPath:=sPathXML) = True Then _
            ds.WriteXml(sPathXML)
    End Sub

  	Public Sub DeleteEmptyNodes()
        Dim ds As New DataSet
        Dim dt As DataTable
        Dim filterStr As String =  "e.EntID IN (SELECT DISTINCT ePrnt.EntID FROM Entity ePrnt LEFT JOIN Entity eCld ON ePrnt.EntID = eCld.EntPrntID WHERE ePrnt.EntType = 1 AND eCld.EntID IS NULL) AS eEmpty ON e.EntID = eEmpty.EntID"

         Dim dr() As DataRow
        Dim sPathXML As String = Path.Combine(Application.StartupPath, "Entity.XML")
        ds.ReadXml(sPathXML)
        dt = ds.Tables("Entity")
        Try
            dr = dt.Select(filterExpression:=filterStr)
        Catch ex As Exception
            MsgBox(ex.Message)
        End Try
    End Sub