Departing board members include Carl Aycock, Max Bobbitt, Franceso Galesi, Gordon Macklin, Bert Roberts and former president and chief executive officer John Sidgmore. Judith Areen also resigned from the board last week.
Only recently appointed members now remain on the board, including former US attorney general Nicholas Katzenbach, former Financial Accounting Standards Board chairman Dennis Beresford, and former Equifax chairman and chief executive officer CB Rogers.
The departing members said they wanted to give Capellas the opportunity to continue reforming WorldCom. A court approved the hiring of Capellas as chairman and chief executive officer of WorldCom this week.
WorldCom filed for Chapter 11 bankruptcy protection in July and is mired in a $9bn (£5.6bn) accounting scandal, the largest in US history. The company faces fraud charges brought by the US Securities and Exchange Commission, several shareholder lawsuits and congressional investigations.