Pompey have announced their retained list ahead of the 2019-20 season.
The Blues have confirmed they will not take up the option of extending Dion Donohue’s deal by an additional 12 months and he’ll be released.
The Welshman moved to Fratton Park from Chesterfield for an undisclosed fee in August 2017, penning a two-year contract.
Donohue made 48 appearances and scored once for Kenny Jackett’s side.
However, the versatile player has been hampered by various injuries this season and featured just 13 times.
Striker Dan Smith will also depart.
The academy graduate spent the majority of the campaign out on loan – firstly at Bognor Regis, while he’s currently at League of Ireland premier division outfit Cork City.
Smith, 19, made two appearances during Pompey’s run to Checkatrade Trophy glory.
Meanwhile, the Blues remain in discussions to extend Nathan Thompson’s stay.
The right-back was Jackett’s first signing after taking over from Paul Cook as manager.
Thompson penned a two-year deal in June 2017 after leaving Swindon and has made 76 appearances and netted one goal at Fratton Park.
Matt Casey has been offered a new deal.
The fledgling defender featured three times for the Blues in the Checkatrade Trophy this term, while he had a successful loan spell at Gosport Borough.
Omar Bogle (Cardiff), Lloyd Isgrove (Barnsley), Viv Solomon-Otabor (Birmingham) and James Vaughan (Wigan) will return to their parent clubs following the end of their loan spells.
Alex Bass, Lee Brown, Christian Burgess, Andy Cannon, Matt Clarke, Ben Close, Ronan Curtis, Louis Dennis, Gareth Evans, Brandon Haunstrup, Oli Hawkins, Jamal Lowe, Craig MacGillivray, Adam May, Luke McGee, Bryn Morris, Tom Naylor, Brett Pitman, Anton Walkes and Jack Whatmough are all still under contract.