There is no remedy to seal the court record. However, an infraction is not a crime so if you were asked if you had ever been arrested or cited for a crime your answer is no. Second, the infraction was dismissed so there was no penalty for the infraction.
An infraction is not a crime, so it won't show up on your "criminal record". I can't imagine that it would have any impact on you getting hired, particularly if it was dismissed. No real way to seal the court record. I suggest not worrying about this. Good luck.