The president certainly has the power to declassify,BUT there is a process to be followed,agencies have to be notified. It;s a bit more than declaring them declassified or doing it just by thinking about it.
The Special Master handpicked by tRump is on record saying if proof isnt provided of Declassification, he will assume they are classified . He also stated that tRump's lawyers have not testified under oath that they are declassified:
Judge
Raymond Dearie, the special master overseeing the seizure of documents from Mar-a-Lago, signaled on Tuesday to lawyers for
former President Donald Trump that if they don’t make a case that any of the documents were declassified, he would determine that they’re classified.
Out of court, Trump has pushed the claim he declassified all the documents, and his lawyers have raised that possibility in court papers, though they have never explicitly argued that anything was declassified.
Federal prosecutors have argued for weeks that documents seized from Mar-a-Lago that contain classification markings – like “top secret” – should be treated as if they are classified.
During a hearing Tuesday, Dearie essentially called Trump’s bluff by pointing out that Trump’s lawyers haven’t yet provided any proof of declassification.
“If the government gives me prima facia evidence that they are classified documents, and you don’t advance any claim of declassification, I’m left with a prima facia case of classified documents, and as far as I’m concerned, that’s the end of it,” Dearie said.