Judith Donovan has resigned as chairman of the Greater Ripon Improvement Partnership with immediate effect.
Mrs Donovan stepped down from the development body after joining the board of the Eden Project in Cornwall.
This new commitment along with her London commitments means she will not be in Ripon enough during the working week to be able to handle the job, she said.
Mrs Donovan added: “It has been a great privilege and enormous fun to chair GRIP. I like to think we have made a difference to some of the economic outlook and we have certainly cemented many key stakeholder relationships.”