A couple things are being confused by the author. Correcting bad memories is one thing. That occurs when we receive new evidence or knowledge that contradicts the memory. This is simply your every day revision of beliefs in practice. Nothing new to see here. But note: there is a justification here. There is knowledge that motivates the revision. There is also good will, a desire to submit to the truth. Willfulness, on the other hand, puts what we want to be the case above what is the case. This is at the core of pride, queen of the vices, and delusion.

"History is not true. You can change history. The actual factual events are such a small part of the story."

Well...no. Facts are a huge page of the story. They're kind of the whole point, if by facts we mean that which is true (the word "fact" is problematic, but the quotation, as well as the title of the article, draw an equivalence between fact and truth). We may not have all the facts, we may be mistaken about them, or we may not yet have inferred some truth. And where we can't reasonable know the truth, we will simply lack that knowledge, leaving us capable of only speculating about possibilities. But there is a truth of the matter. It's not whatever you want it to be.

Once in the past, facts are immutable, as it were. That the past only exists as a memory does not give you license to toy with that memory in one direction or the other, in your (ostensible) favor. I say "ostensible" because willful self-deception (which is what attempts to tweak memories is) does a few things that are harmful. First, it destroys our connection with reality. I don't think I need to explain why that's bad. Second, denial is repression of uncomfortable truths (or at least what we hold to be true), and not like overwriting a file on disk. It's more like sweeping a dangerous animal under the rug. It reach out from under and bite you, you will trip over it even when it is sleeping. Occasionally, it will lash out from under the rug and cause terror. There will always be a lingering anxiety about the ever present possibility that it will escape from under our control and attack us or something we care about. A repressed truth introduces all sorts of weird tensions into the psyche, perverting our perception of reality, enslaving us to fear. That's the paradox: caging uncomfortable truths makes them our greatest enemy and gives them power over us. Acknowledging them sets us free. Repression is only something we use to suppress inappropriate impulses or desires (the basis for self-discipline and the moral life), not the truth; indeed, failing to repress inappropriate impulses alienates us from the truth, not least of all because it entails a repression of the truth to enable the indulgence of that desire and a weakening of the intellectual faculties. Repressing guilt always leads to self-destruction. It's why human history is full of human and animal sacrifice. (It's also why, in Christianity, God provides Himself as the perfect sacrifice, as the Lamb of God, bloodlessly offered at each Catholic mass on the altar, and why the sacrament of penance exists: to accuse oneself before God and receive absolution.) Guilt will destroy you, but denial only doubles its power, not to mention the added guilt of having repressed the guilt. The psychotherapy industry is funded by the guilty conscience. But if you think denial is some kind of escape hatch, sorry. That ways lies madness.