The departure of Pittman, who ran Internet provider America Online before the takeover of Time Warner in 2001, emphasises the demise of the multi-media strategy behind AOL's £100bn takeover of Time Warner's traditional media and entertainment businesses.
The announcement came following an AOLTW board meeting today, in which the board was expected to discuss an executive shakeup.
The company announced that Pittman is stepping down as both chief operating officer and as a director of AOLTW, and will leave the company once a replacement for AOL chief executive officer Barry Schuler is found. Schuler quit AOL in April.
AOLTW is due to release its second quarter results next week. The company has denied US newspaper allegations that it undertook "unconventional transactions" to boost its sales.