Powell first joined the Magpies on a youth loan back in July.
He went on to make 11 appearances in all competitions for the Pitching In NPL Midlands Division side.
On Powell's departure, Magpies boss Tom Parke said: "It's been a pleasure to work with Aaron. He is a very talented footballer and has really matured as both a player and a person in his time here.
"I have no doubts he will kick on and achieve whatever he sets his mind to in the game.
"It's a shame we couldn't play Aaron as much as we would have wanted to, but the experience for both the football club & Aaron has proven valuable."
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