There are no official ways of disabling the ME.

The Coreboot project and the Hardenedlinux project have worked on it, and here are some resources on their progress:

https://hardenedlinux.github.io/firmware/2016/11/17/neutrali...

https://www.coreboot.org/Intel_Management_Engine

And here is a general writeup on the Intel chips and their "features": https://libreboot.org/faq.html#intel

If Intel aren't going to patch old systems, here to hoping that they will let us disable it, but it probably won't happen.