The 26-year-old's deal had been due to expire in summer 2019.BCFC
The 26-year-old's deal had been due to expire in summer 2019.
Brock-Madsen was originally signed by Blues in August 2015 by former boss Gary Rowett.
However he didn't make the impact both parties hoped for and racked up just eight appearances during his three-and-a-half years with the Club.
His last Blues appearance came in a Sky Bet Championship home fixture against Hull City in December 2015.
Having failed to claim a regular starting place with Blues, the former Denmark Under-23 international spent three extended spells out on loan with other clubs.
These were with Dutch side PEC Zwolle, Polish outfit Cracovia and more recently this season Scottish Premier League club St Mirren.
When Brock-Madsen's International Loan to St Mirren expires on 1 January, 2019, he formally becomes a free agent.
The Club took the decision to initiate this course of action as part of the continual commitment to managing costs and a considerable saving has been made in this instance.
Blues would like to place on record their thanks for the professionalism displayed by Brock-Madsen and wish him every success in his future footballing career.