Capellas was formerly CEO of Compaq Computer Corp., which merged with HP in May.
HP said Capellas had fulfilled an agreement to stay with the company through the merger and is leaving to pursue other career opportunities. The company declined to comment on where Capellas will end up. It has been reported that he is leaving HP to join troubled WorldCom.
The president's position will not be filled, leaving CEO Carly Fiorina in charge of the company.