Quartet released by Fleetwood
Shaun Beeley is one of four players that have had their contracts terminated by Fleetwood.
The League Two have also mutually terminated the contracts of winger Ryan Crowther, striker Steven Gillespie and forward Alex Titchiner.
Full-back Beeley recently returned from a loan spell with Bury because of a hamstring injury and departs Highbury having made over 200 appearances for the Cod Army.
"This is just a part of football and each club has a turnover of players," Alexander told the club's official website.
"All four are good lads and I'm sure they'll each find a club and continue their respective careers. Shaun, in particular, has been at the club a long time and enjoyed success. We genuinely wish them all the best."