Though there aren’t specific protocols that the president must follow to declassify a document, federal courts have ruled that they will “refuse to recognize what they consider to be an inference of declassification,” McClanahan said (Kel McClanahan, executive director of the National Security Counselors).
The U.S. Second Circuit Court of Appeals wrote in a 2020 decision about whether statements made by then-President Trump declassified the existence of a CIA program that “declassification, even by the president, must follow established procedures.”
And saying it two years after he's out of office DAMN sure don't make it so!