Manley started 12 games for the Aggies last fall and completed 53.9 percent of his passes for 2,764 yards and 18 touchdowns.
The junior-to-be was locked in a three-way battle for the starting quarterback job this spring with Travaughn Colwell and Andrew McDonald, but he appeared to not be a great fit for the offense installed by new coach Doug Martin.
"We wish Andrew all the best," Martin said. "Obviously with all the changes in the offensive system he didn't fit in as well the way he may have in the past. The competition at quarterback was going to be tougher for him this season, as well as some of the family matters he has, he wanted to get closer to home. We support Andrew and his decision."
Manley will have to sit out one year before he is eligible to play at another FBS school.