Delete menuitem from dockingmenu

Hi,

In the 2015 version i can remove a specific menuitem with the following code

            For curPos As Integer = e.ContextMenu.Items.Count - 1 To 0 Step -1
                Dim mnuItem As MenuItem = TryCast(e.ContextMenu.Items(curPos), MenuItem)

                If mnuItem IsNot Nothing Then
                    Dim mnuCmd As RoutedUICommand = CType(mnuItem.Command, RoutedUICommand)

                    If mnuCmd.Name = "MoveToNewHorizontalContainer" Or
                       mnuCmd.Name = "MoveToNewVerticalContainer" Then

                        e.ContextMenu.Items.Remove(mnuItem)
                    End If
                End If
            Next

Now in the 2016 version i cannot use anymore the CType(mnuItem.Command, RoutedUICommand). How I achieve the same in the 2016 version?

Thanks
Marcel