Or, as the iol report notes
A party spokesman said the process had now started and confirmed Mr Adams had written to Westminster to formally resign.
Here’s Mick’s post in November on the republican’s dilemma.
From the factsheet [pdf file]
A Member wishing to resign applies to the Chancellor of the Exchequer for one of the offices, which he or she retains until the Chancellor appoints another applicant or until the holder applies for release from it. (Every new warrant issued revokes the previous holder). It is usual to grant the offices alternately; as this enables two Members to retire at precisely the same time. Indeed, on 17 December 1985, fifteen Ulster Unionist MPs resigned on the same day.
Upon receipt of a Member’s application for the Chiltern Hundreds, a warrant of appointment is signed (in the presence of a witness) by the Chancellor of the Exchequer. Since 1850, these have been registered and retained in the Treasury. On the day the warrant is signed a letter is sent to the Member, omitting the letters MP after his name, to inform him that he has been appointed to the office. Letters of notification are also sent at the same time to the offices of the Speaker and the Government and opposition whips. As soon as practical, the appointment is noted in the London Gazette. It is also the practice for the Treasury to issue a brief press notice. The disqualification of a Member because of his new office is recorded in Votes and Proceedings although there are no proceedings in the house and it is not recorded in the Official Report.
If a Stewardship is granted during a recess, the new writ for a by-election cannot be issued until the House meets again. If it is granted during the session, the party’s whip is free to move for a new writ immediately after the Chancellor of the Exchequer has signed the warrant of appointment (see also Factsheet M7 Parliamentary Elections).
Adds Here’s the relevant legislation – House of Commons Disqualification Act 1975 as amended and in force today within the United Kingdom.
And It looks like the Stewardship due up next is the Crown Steward and Bailiff of the Manor of Northstead.