Remove Domain Users Group from User in AD via VB.Net

Group,
  Can someone help achieve this through VB.NET, I don't speak C#

  I am able to add a user in AD, add a second security group, set the new group as default, but then I cannot remove the old default group.  If I go thru AD interface the group will remove.  I have tried several versions of code that all generate errors.

  Any help appreciated.

Code -----------------------------------

Public Shared Sub RemoveDU(ByVal Login As String)

        Dim de As DirectoryEntry = GetDirectoryEntry()
        Dim deSearch As DirectorySearcher = New DirectorySearcher(de)
        deSearch.Filter = "(&(objectClass=user)(samaccountname=" & Login & "))"
        deSearch.SearchScope = SearchScope.Subtree
        Dim deSearchResult As SearchResult = deSearch.FindOne

        If Not deSearchResult Is Nothing Then
            Dim dey As DirectoryEntry = GetDirectoryEntry(deSearchResult.Path)

            Dim deDomainUsers As DirectoryEntry = New DirectoryEntry("LDAP://xxx.xxx.xxx.xxx/CN=Domain Users,CN=Users,DC=xxx,DC=org")

            'Remove the User from "Domain Users" group
            'deDomainUsers.Children.Remove(dey)   - tried this as well
            deDomainUsers.Properties("member").Remove(dey.Path)

            deDomainUsers.CommitChanges()  - fails here

            deDomainUsers.Close()
        End If
        deSearch.Dispose()
        de.Close()
    End Sub