As I understand it, Dodd-Frank is a law passed by Congress. Before such a law goes into effect, it is signed by the President, allowed by the President to pass into law without a signature, or subjected to a presidential veto which was overridden by a supermajority vote in both houses.
Parts of its implementation can be reversed through executive orders, but to get rid of it completely requires that it be overturned, either by the courts or by a new law repealing and/or replacing it. If this were not the case, any president could wipe out any law he disagrees with solely by issuing executive orders.
All that being said, I do hope to see significant parts of it dismantled. We're running very short on US regulated forex brokers, so some form of mutually agreeable exchange of recognition of regulation with one of the better non-US regulators would be a very good thing now.
And, yes, mortgage derivatives rank right up there with a killer asteroid in terms of things which could end civilization as we know it. However, a lot of banks and a lot of investors are happily making profits now, so shutting this sort of thing down won't be easy.