Hull have released Australian halfback Brett Seymour with 18 months left on his contract.
The 28-year-old has been battling with depression and has been on compassionate leave since being involved in a traffic accident in March.
Hull director of rugby Shaun McRae said: "Brett is at a stage where he needs to be concentrating on a number of important aspects of his life other than rugby league.
"He leaves Hull FC with our best wishes for the future.''
The former Brisbane and Cronulla halfback joined Hull from New Zealand Warriors on a three-year deal at the start of last season but has struggled to hold down a regular place in the team.