Simms has been at Thrum Hall for two and a half years, but said yesterday: "I've taken the club as far as I can and the time is right for some new blood to be brought in and build on the firm foundations that have been put in place."
Sunday's Cup exit, after scraping through against Hull KR in the previous round, was a bitter blow and if Simms had not resigned he may well have been sacked.
David Hobbs, Halifax's football manager, has taken temporary charge of team affairs, but is not thought to want the coaching job permanently. The prime contender for the vacancy must be Graeme West, who split with Wigan last week.
Castleford have put their Great Britain tour scrum-half, Tony Smith, on the transfer list at pounds 150,000. Hull have renamed themselves the Hull Sharks.Reuse content