Others have pointed this out before, but let me reiterate the point. The President of the United States is the ultimate arbiter for what is and is not classified; by law. He can and does delegate some of that responsibility and authority to his cabinet members such that they may classify or declassify anything that is within their purview. If the POTUS discloses classified information then it, from that point, becomes unclassified. Also, if the SOS has classified some information then she/he may declassify it on a whim. However, the only time this will become an issue is if the SOS reveals information that is classified by another department such as DOD. Downgrading/declassification usually goes thru a procedure that determines if revealing the information will do damage to the USA but that only applies to us little people.
“If the POTUS discloses classified information then it, from that point, becomes unclassified.”
That is incorrect. The POTUS CANNOT unilaterally change the classification on anything classified. The ORIGINATOR of the classified information is the only one that can downgrade it. The originator can be a person (usually the person who sourced it) or the agency with which the information derived, normally it’s the agency. Obama is guilty, period.