The management engine cannot be completely disabled in intel chips that ship with it because some of the things it handles are required for the chip to actually work. Really, you are better served by getting a chip without a management engine. Most AMD chips have their own version of the intel management engine, so they aren't safe. ARM boards are usually a little safer but not all. All of the Apple chips have a technology very similar to management engine built in. I don't know about the RISC-V boards but they are borderline trash so far anyway so they aren't a great escape route either.