BirminghamLive reports the teenager has been released just a year after he arrived at Old Trafford from Leeds United.
He is one of several players currently on trial with the club's Under 23 set-up as Garry Monk works with Richard Beale and Paul Robinson to put his stamp on the club. Richardson is currently looking for his next club having also attracted the interest of Queen's Park Rangers.
The 19-year-old spent time in the Leeds academy before being snapped up by their deadly rivals last summer after impressing during his trial with the Red Devils. Striker Evan Pierce is also on trial after being released by West Brom at the end of the season.