Thinking about selling than old Android (NASDAQ: GOOG) for some cash? Think again. According to a new technology study, reverting your phone back to its "factory settings" does not necessarily delete all of the data on the Android phone, CNN Money reported. Information like contacts, photos and web history may still remain on the phone. Some of the phones used in the study include HTC One, HTC Sensation XE, Motorola Razr I and Samsung Galaxy S. However, not every phone had the same problems, some were able to recover more or less information than others. "This can be desperately complicated," said Ross Anderson, a Cambridge engineering professor, CNN reported. "Don't hand off your old phone. Smash it." For more business and financial news, click here.