Per the Presidential Records Act of 1978, Presidents and Vice Presidents must turn over all of their records to the National Archives upon leaving office.
The safeguards put into place by the United States Constitution to prevent absolute power in the hands of the Executive Branch are being threatened.
Here is the full text of the speech Bernie Sanders made at Liberty University. He was speaking to a notoriously conservative, very religious crowd with whom he shares differing views on many issues – but he spoke with honesty in an effort to find common ground. I think he probably found it.