He will leave at the end of February after four and a half years at the firm.
His post is one of many scrapped after Carphone Warehouse acquired AOL's UK internet access business last October.
AOL UK chief marketing officer Tobin Ireland has also taken redundancy.
The press office is now manned by two staffers - senior manager and head of audience PR Cass Stainton, and communications executive Jennifer Higgs.
Lambeth said a finalised marketing and comms structure would be determined in the coming weeks. AOL UK does not retain a PR agency. Lambeth said the firm's contract with Shine Communications ended last December, while other agencies - including Freud Communications and Blue Rubicon - had not been retained for the UK since 2004 and 2005 respectively.
He added that a new head of marketing, once installed, would make a decision about whether to take on a new agency.
Lambeth said the redundancy was ‘well-timed', as he moved to Dorset last November. He intends to go freelance. He said: ‘I have a long-term plan to focus on environmental, sport and political areas to broaden my new-media, technology and telecoms background.'
Prior to AOL, Lambeth was a journalist for eight years, latterly working as a reporter on The Daily Telegraph's City desk.