The company said he was leaving to pursue other interests.
Mr Fenton was in charge of the company’s southern region. He had been with the company since 1983 and a board director since 2003.
His opposite number in the north, Steven Boyes, is taking over all housebuilding operations in the new role of chief operating officer.
The company did not make clear whether the restructuring was already planned and there was no longer room for Mr Fenton, or whether the restructuring was a response to his departure.
However, a statement from chief executive Mark Clare seemed to suggest that it was all planned: "Steven is one of the most respected operators in the industry and has a wealth of housebuilding experience, having joined the group in 1978. The revised operating structure will drive further standardisation, cost efficiency and quality improvement across the group and underpin the delivery of improved profitability and reduced net debt."