The move came after talks between Kocaman, Koc and the Fenerbahce administration, the chairman said, thanking Kocaman for his contributions to the club as both player and coach.
"We have reached an understanding that our football team needs to open a new page in terms of leadership," Koc said in a statement on the team's website.
Kocaman, who resigned from the club in 2013, led the team to a trophy-less season. Fenerbahce finished second in the league, behind bitter rivals Galatasaray, and lost in the Cup final to Akhisar Belediyespor.
Fenerbahce this month elected Koc, a businessman from Turkey's wealthiest family which runs the Koc Holding conglomerate, to replace Aziz Yildirim as chairman after two decades.
(Reporting by Tuvan Gumrukcu, editing by Ed Osmond)
