But he did not explicitly apologise for having used the word, which led a majority of his colleagues to vote for him to “not be further heard” for the rest of the session.
The incident took place during a debate about the Assembly’s scrutiny of the Met Police.
Mr Devenish had put forward a motion noting “huge regret that the Met Police Commissioner has all but withdrawn along with his Deputy Commissioner from regular attendance” at meetings of the Assembly’s police and crime committee.
The committee is chaired by Ms Russell, who insisted that the committee was working to ensure that the commissioner continues to regularly attend its sessions.
As she concluded these remarks, Mr Devenish could be heard calling her “deluded”, prompting Ms Russell to demand an apology from him.
When no apology came, Labour group leader Len Duvall called on Assembly chairman Andrew Boff to “take some action”.
Mr Boff invited Ms Russell to finish her remarks. Liberal Democrat group leader Caroline Pidgeon then asked for details on how assembly members can be removed from the chamber.
Following an explanation from the Assembly’s clerk, Mr Boff asked whether Mr Devenish would like to say anything.
Mr Devenish said: “If you wish to do this chair, that’s absolutely fine. I’ve found working with Caroline so difficult during the year. I’m very happy to be removed, frankly.”
The chairman said that removing or silencing Mr Devenish should be “a last resort”, and asked him whether he admitted to using the word “deluded”.
He replied: “I’m happy to withdraw that word, chair.”
But Labour member Leonie Cooper said that this was not an apology. A motion for Mr Devenish to “no longer be heard” was put forward by Green member Sian Berry, seconded by Ms Pidgeon.
The Assembly voted by 14 votes to six in favour of the motion, leading Mr Devenish to walk out of the meeting.
Mr Devenish’s motion - about the Met’s willingness to send senior officers to answer questions at committee sessions - was passed with 15 votes in favour and five abstentions.
Met commissioner Sir Mark Rowley prompted concerns from within the Assembly when he told them in September last year that he may have to attend its sessions less often, if his time is occupied by the new London Policing Board.