12th April 2016, 11:28 | Wakefield
The Wildcats signed the 26-year-old in the close season on a 12-month deal but he has yet to play for them and the club say he has now been released by mutual consent.
Morris, who made eight appearances for the Broncos in 2015, said: "Under medical advice I have decided to take a break from the game for the foreseeable future to make a full recovery from my head injury.
Wakefield Wildcats can announce that Sean Morris has left the club by mutual consent https://t.co/osVC4mCE42— Wakefield Wildcats (@WTWildcatsRL) April 12, 2016
"I would publicly like to thank chairman Michael Carter, the club and coaches for their support over the past few months with my recovery and going into the future.
"I will always look back to my time here and wish that I had been able to pull on the red, white and blue shirt, but the boys know that they have got my continued support and I wish everyone at the club the best of luck."
Morris began his career at Kingstone Press League 1 club Oxford before going on to have two stints with the Broncos.
Wakefield chairman Michael Carter said: "I would like to wish Sean all the very best for the future.
"It is very unfortunate that we did not see him pull on the red, white and blue shirt but his long-term health and well-being is of the utmost importance. Common sense dictates that we follow the medical advice."