Has Trump actually written a second E.O. that revoked Obama’s DACA E.O.?
I don't think so.
If I am correct, all Trump needs to do is write a new E.O. to reverse the judge.
I will speculate he did not write a new E.O. because he does not want to allow political opponents to say "Trump revoked DACA."
Instead, I think he just tossed the DACA issue to Congress, and arbitrarily set March 2018 as the cut off date, with no E.O.