Just to clear matters up a bit, President Trump did not himself release the final collection of JFK related documents housed by the National Archives – Congress did, back in 1992. In 1992, Congress passed a public law – “President John F. Kennedy Assassinations Records Collection Act of 1992” – directing the National Archives to establish a collection consisting of copies of all U.S. government records relating to the 1963 assassination of President Kennedy. The record collection includes materials from Federal agencies as well as state and local law enforcement.
The Act also created the Assassination Records Review Board (ARRB), chartering it to collect relevant documents and to issue decisions on agency requests to withhold or postpone document release. At that point in time, 1992, 98% percent of all Warren Commission documents on the assassination had already been released. The ARRB released all the rest of the Warren Commissions documents to the general public – other than individual income tax returns. The ARRB also collected additional materials from federal agencies as well as from individuals, including testimony from individuals directly involved as eyewitnesses, participants in the investigation and the treatment and autopsy of the President following the shooting.
The 1992 law required that all documents be released to the public by October, 2017. The great majority (88%) had already been released by the late 1990s. As of 2017 only 35,000 documents remain to be released in full; some 3,600 have never been seen by the public. The final NARA releases actually began in July of 2017 and some 3,000 have already been released as of early October. For details on what that release involved and what is especially interesting in the first batch released readers should check the information on the Mary Ferrell site:
The 1992 act called for release of all documents, however it contained the provision that the President of the United States could act to postpone documents if they were continued to cause harm to military, intelligence, law enforcement or foreign relations activities of the United States and such harm is judged to be of such gravity that it outweighs the public interest. President Trump chose not to exercise that authority, simply allowing the general release to go forward.
It also needs to be pointed out that over the years dedicated researchers have located relevant documents which were not supplied to NARA as part of its JFK collection; some of those have been and continued to be pursued via FOIA and legal appeals related to agency refusals to release under FOIA.