Is a small S-Corp, located in California, with two owners (50% each) who are also the two directors and the only two W-2 employees, required to have Workers Comp?

There are no other employees or contractors besides the two owners. The two owners don't need/want the Workers Compensation insurance. And, if not required by law, is there any form that need to be filed to formalize the opting out from Workers Comp? Thanks,