"We're grateful to him (McClaren) for all his efforts during his time with us," club CEO Lee Hoos said in a statement.
"It's well documented that we're in a period of transition as we work hard to make the club financially stable. With that comes challenges, not least the cutting of the wage bill while aiming to remain competitive.
"As we look to the future, and taking recent results into account, we feel now is the right time to re-evaluate where we are."
McClaren, a former assistant to Alex Ferguson at Manchester United, was England's manager between 2006 and 2007 but his 18-month tenure ended after they failed to qualify for the 2008 European Championships.
(Reporting by Rohith Nair in Bengaluru; Editing by Christian Radnedge)
