That is simply not true. He would only be able to declassify that which he originally classifed, as the classifying authority. If he wished to declassify something that had been classified by another classifying authority, he would have to go back to that original authority to have it declassified. It's really not a one man show.
What you are saying is that he has the same authority as the President. And I'm still not sure that the President has the authority to wave a magic wand and declassify anything he likes - because it goes back to the protection of means and sources which is the upmost of importance. Particularly when/if hyou are dealing with TS/SCI. I really don't know if the President and or VP are "read in" on all of the SCI programs. That's the reason they are specially compartmented, so that only a few people are read in.