Quantum Mechanics is the weirdest thing I have ever known..Seriously the entropy stuff didn't make any sense at ALL! I recommend you watch this video, at a point it explains about entropy stuff too (but they don't mention this term).
In information theory and in thermodynamics, entropy basically describes a lack of knowledge. An object doesn’t really possess entropy, but rather its entropy is dependent on the observer. The observer (human) will realise that the memory (another observer) will have more lack of knowledge (lower entropy) and thus he can delete the data from the memory with less energy expenditure.
Enter Quantum Mechanics. If the deleter has the perfect classical knowledge of a system, deletion of data could theoretically happen with no energy at all. And if the deleter of the system has more than complete classical knowledge (i.e.,
is entangled with the system at the quantum level), then the deletion will actually remove heat from the system.
If this stuff doesn't make sense to you, don't worry it doesn't make sense to anyone.