Dim dir As String = ... // какая-то папка
        Dim ftime As DateTime

        For Each fname In Directory.GetFiles(dir, "*.txt")
                ftime = File.GetCreationTime(fname)
                If DateDiff(DateInterval.Day, ftime, Now) > 2 Then
                    File.Delete(fname)
                End If
        Next

        Dim dir As String = ... // какая-то папка
        
        For Each fname In Directory.GetFiles(dir, "*.txt")
                Dim ftime As DateTime = File.GetCreationTime(fname)
                If DateDiff(DateInterval.Day, ftime, Now) > 2 Then
                    File.Delete(fname)
                End If
        Next