The bottom is quite easy to take off, just some screws around the perimeter and you’re in. You can unplug the battery pretty easily but it’s harder to remove as it’s glued down. Also I’m pretty sure MacBooks severely underclock the processor if there’s no battery so your performance may suffer. Been through the same thing with my 2013 MacBook Pro. It’s a Linux mint server now.
I’m not 100% sure but which power source you are using, and whether or not the battery seems more like a BIOS or SMC thing, so I’m not sure if even Linux would be able to access it. I could also be totally wrong
You can very easily turn it off with the control center (swipe down from top right of screen) toggle. You can also set certain apps/people to be able to contact you even when on. You basically have complete control of everything.