By Adam Whittaker

BP said its deputy chief executive, Carol Howle, plans to retire later this year, leaving new boss Meg O'Neill without an experienced executive at a time when the energy major has been hit by management turmoil.

Howle's retirement after more than two decades at BP marks the latest departure at the top of the oil company. She was only formally appointed deputy CEO in April after serving as interim CEO since December last year, when Murray Auchincloss stepped down after less than two years at the helm of the business.

When O'Neill joined to lead BP in April, Howle agreed to support the transition as her deputy but it was decided she would step down once the handover was complete. During this period she has overseen a portfolio review and long-term strategy development. She will step down in the third quarter.

O'Neill said Tuesday that she won't appoint another deputy CEO. The company is in the midst of an organizational restructure designed to simplify decision making, she said.

BP has suffered years of management upheaval and operational disasters. It is currently pruning its portfolio and cutting debt in a bid to boost shareholder returns.

Turmoil at the top of the business continued in May when the company's board ousted its chairman Albert Manifold after it received whistleblower reports that he was bullying and verbally abusive toward staff, according to people familiar with the matter. Manifold later rejected what he described as lies about his behavior.

The company has now had four chief executives and three chairmen since 2023, including interim roles.

Howle also runs BP's vast trading and supply business. She will be replaced by Sam Skerry, who currently serves as head of M&A at BP. Skerry previously worked across the trading business.

BP has also appointed Sonya Adams as head of people and culture. Both Adams and Skerry's appointments are effective Aug. 1.

Shares were down 1% at 467.8 pence in afternoon trading.

Write to Adam Whittaker at adam.whittaker@wsj.com