By Malathi Nayak SAN FRANCISCO (Reuters) – Zynga Inc co-founder Mark Pincus is relinquishing the last of his operational duties at the social gaming company starting on Wednesday and retreating to an advisory role as Chief Executive Officer Don Mattrick pushes through a restructuring plan. Zynga shares were up 5 percent in after-hours trading on Wednesday after closing at $4.42 on the Nasdaq. Pincus, who remains chairman of the board, has decided to move on from day-to-day operations as chief product officer, Zynga said in a statement. He has been stepping back from the company that once dominated gaming on Facebook with Farmville and raked in over $1 billion in revenues, but is losing users to mobile game developers.