As reported by The News, Storey is one of a host of youngsters leaving in a major academy player overhaul.
The midfielder, along with fellow Ulstermen Eoin Teggart and Harry Anderson, were told by the Blues they were not being handed new deals last month.
In addition, Harry Kavanagh, Charlie Bell and Harvey Rew have been told they’re being released, while Alfie Stanley’s future is in doubt.
Storey joined Pompey from Portadown in the summer of 2019. He made one appearance at Pompey, arriving off the bench in a 3-0 win at Cheltenham in the Papa John’s Trophy this season.
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Storey’s been on loan at Irish Premiership side Carrick Rangers since January – and won’t be returning to the south coast.
And the Northern Ireland says he’s excited for his next challenge after spending two years at Fratton Park.
He wrote on Instagram: ‘Just want to say big Thankyou to @officialpompey and everyone that’s helped me over the last 2 years, it’s been an amazing experience to say the least.
‘I come away from the club with new memories, friends, family that will last a lifetime but unfortunately it’s time to say googbye.
‘As one door closes another one opens, I can’t wait for a new challenge and to see what’s next.’