Hetherington became the coach in July 1986. Sheffield gained promotion to the First Division in 1989 and, despite being relegated two seasons later, returned last year.
They won the Stones Bitter Premiership for the lower divisions in 1989 and 1992, and last October reached the Yorkshire Cup final where they were beaten by Wakefield Trinity.
'The time for a change is right for me and the team,' Hetherington said. 'I will spend time generating the ever-increasing financial requirements to sustain the club's ambitions.
A new coach is expected to be announced next month. 'We now need a successful and experienced coach who can bring a fresh approach and build on what the team has achieved,' Hetherington said. 'I hope to return to coaching in the future - that is where my ambitions lie.'Reuse content