Quite obviously, it cannot be true. While some few schools or proponents of psychology deny the subconscious mind exists, it is mighty hard to explain more than a hundred years of experiences, observations, experiments and facts without one.

If the subconscious mind does not exist, then hypnosis, NLP and subliminals must all be invalid. However, properly implemented, they all do work, and this has been known for over a hundred years (in the case of hypnosis). The earliest specific research into subliminal perception that I have been able to find mention of points back to the 1880's, and NLP is younger still coming from the middle of the 20th century. But these things are all well known to work, and cannot be explained without the existence of a subconscious mind.

The subconscious mind does indeed exist, and it is evidenced every day when someone does something without consciously thinking about it.

It is impossible to explain how an ultrasonic subliminal that a person is not even aware consciously is being played can result in their successfully stopping smoking permanently - which I have seen happen in experiments - if there is no subconscious mind, especially considering the way the subliminal was built. To the conscious mind, it sounds like pure gibberish; one observer said it sounded like water or rainfall. And that's not the only thing we have observed to happen from consciously undetectable subliminal messaging.

My conclusion? There is a subconscious mind, and I don't see how anyone, no matter what their credentials are, can reasonably deny it with a straight face.