The departure was due to personal reasons, says the report, citing an unnamed source.
Zadesky, formerly involved with the iPod and iPhone teams, is said to have been placed in charge of Project Titan, the Apple electric car project, in 2014.
Importantly, the report also indicates that engineers on Project Titan are hitting setbacks beyond merely the departure of Zadesky - Apple's top brass is reportedly being unclear on the project's goals and asking for unrealistic deadlines.
While the company has yet to announce a car, Tesla CEO Elon Musk recently described Apple's plans for an electric car as an "open secret" in the industry, even as Apple hires ex-Tesla engineers and other experts to further its automotive ambitions.
Project Titan is said to have a ship date of 2019, though as the report notes that in Apple parlance, "ship date" just means that this could be when Apple engineers finalize the features and design of the car.