Theo Widdrington is set to be released by Pompey.
The midfielder has announced he will leave the club on Twitter.
Widdrington graduated from the Blues' academy and signed his first professional deal last summer.
But Pompey have opted not to take up the option of a further year on the Eastbourne talent's contract.
On Twitter, Widdrington said: 'It's been an amazing 13 years at an amazing club.
'I'd like to say thanks to all the staff, players, friends and family who have helped me to where I am today.
'It's time for a new challenge now! I wish everyone involved at the club all the best for the future.
''I'm forever grateful and will cherish all the amazing memories I've made at Portsmouth #PUP.'
The 19-year-old spent the first half of the season on loan at the Hawks.
He played 23 times and scored three goals in their push for the National League South title.
Yet Widdrington was recalled by Jackett in December to help ease Pompey's injury problems.
He was named on the bench eight times but never made a first-team appearance.
Nevertheless, he was a regular for the under-23s in the Premier League Cup and Central League Cup.