So we as viewers and the Avengers as a whole of course know that Tony Stark created Ultron. The question is, is the general public aware of this?
There is no evidence that the public is aware.
Nothing in the films (Age of Ultron and Civil War) or in their scripts suggests that the general public knows anything about Tony Stark's direct involvement in the creation of Ultron.
In Civil War, the public seems to be concerned only with the collateral damage caused by the Avengers' missions. Consistent with this, the Sokovia Accords seem to be focused squarely on limiting this kind of damage (particularly on foreign soil), by controlling when and where the Avengers are deployed.
If anything, Tony Stark seems as popular as ever, given Peter Parker and Aunt May's reaction to him.