ZURICH—Nestle is overhauling its geographic structure, the world’s largest food company said on Wednesday, creating new zones for North America and for Greater China. The maker of Nescafe instant coffee and KitKat chocolate bars also said it was changing its executive board to align with the new structure, which takes effect from January. Company veteran Chris Johnson, now head of Nestle’s Asia, Oceania and sub-Saharan Africa zone (AOA), will retire from the executive board and be replaced by Remy Ejel, current head of Nestle’s Middle East and North Africa business. Steve Presley, chairman and CEO Nestlé USA, will join the executive board as CEO Zone North America, Nestle’s biggest market with annual sales of 24.7 billion Swiss francs ($26.59 billion). David Zhang, CEO of Nestle’s food seasoning business Totole and business executive officer for food in Greater China, will join the board as the head of the Greater China business. …