The A's designated Harris for assignment on Saturday.
Harris, who has been with Triple-A Las Vegas since May 12, has now lost his place on the 40-man roster. The 28-year-old recorded just six plate appearances for the big-league club this season, but with Las Vegas, he slashed .336/.441/.537 with five homers and 34 RBI in 178 plate appearances. The Athletics designated Harris in order to make roster room for their new acquisition, Hayden Juenger.