Brass joined the club as part of Alan Knill's backroom team, becoming assistant manager. Neil Cutler also joined the Iron as goalkeeper coach.
Neither left when Knill was sacked as manager in November, but Brass has now left Glanford Park.
"The difficult decision was taken to reduce costs going forward as the club cannot sustain two assistant managers long term," they said in a statement.
"The club would like to place on record its appreciate for all the hard work Chris has put in during his time with the club and wish him well for the future."