Wow, you have many issues here. Let’s start with the insured/self-funded issue first. What does the plan documents say about this? Level funded is a relatively new term, and some people use it loosely, when I started in 1982 we called them retrospective arrangements. But I would assume it is self-insured.
As for MEWA, there is no requirement that I know of that requires contracts to be insured, now your state may be different, but I doubt it. So following that logic, and assuming it is self-insured, there is no need to follow state regulations because ERISA governs.
If you are trying to exit the contract early keep in mind the self-insured contract will more than likely expose you/employer to the claims costs.
Lastly, I would double check the program structure and verify that it is in fact a MEWA. A recent innovation has been the use of a captive to fund benefits. These captives have multiple employers participating.
Good luck, and I am available to discuss on phone if you would like.