Roy, a 6-foot-6 swingman from Garfield High School, notified league officials in a letter last week, and his family received a letter Monday confirming that he had been removed from the draft pool.
Roy was mostly testing the waters with his application to go directly from prep to pro ball, his father, Tony Roy, told The Seattle Times.
"It was basically just that, an experiment," the elder Roy told the newspaper. "We think whatever we got out of it has been positive."
Last month Roy took advantage of a new NCAA rule that allows high school seniors to enter the draft and be chosen without losing their college eligibility so long as they do not sign with an agent or team.
Roy's lone workout for an NBA team was with the Portland Trail Blazers last month. He was among the roughly 60 prospects who were invited to Chicago for the predraft camp.
By removing himself from the draft, Roy eliminated the risk of having to make a difficult choice had he been chosen in the second round.
Second-round picks are not guaranteed contracts, and a team that drafted him would own his NBA rights until one year after his college eligibility expired if he opted for college.
Roy, 17, graduated from high school Saturday. He has accepted a basketball scholarship at Washington but has yet to receive a standardized test score that would make him eligible to play as a freshman.
If he does not receive a high enough score on his latest test, he won't enroll at Washington this fall but will take the test again in October, when a qualifying score would enable him to enroll in the next quarter, his father said.
"The coaches have been really positive about it," Tony Roy said, "and they're welcoming him back and looking forward to the future. I'm looking at it as a dad, and I think college is a great opportunity."