PARIS—The governor of France’s central bank on Friday told President Emmanuel Macron that the country’s heavy public debt, bloated by spending to safeguard jobs and growth during the pandemic, posed a challenge to the economy but could not be cancelled. In his annual letter to the president, Governor Francois Villeroy de Galhau said easing the debt burden would need time, economic growth spurred by investor-friendly reform and more efficient public spending. “Cancelling the debt is not an option,” the governor wrote. Villeroy said this did not mean fiscal austerity. “It is about striving for stability, first fiscal stability, by excluding tax increases and also cuts that we cannot finance, and secondly stability in the volume of public spending,” he continued. France went into the pandemic with public debt at 100 percent of national output, exceeding the euro zone average, and is projected to close 2021 at close to 120 percent …