[Someone]

(Slight) nitpick: unless you destroy it, it wont shut down completely. Modern hardware never shuts down completely in normal operation. There always is at least some tiny CPU that listens for, say, wake on lan or activity from a Bluetooth keyboard.

Macs also can be configured to wake up to download updates.

As to company software: depending on the country you’re in, your employer may be required to tell you beforehand when they do. If they didn’t they still may be collecting data (either by accident or on purpose), but they won’t be allowed to use it.

If you’re concerned about your employer knowing where you are, leave the laptop at the office or at home.

[Engineering-MD]

Removing the battery should help (assuming no back up or remove those also)

[NullPrefix]

Macbook batteries are not easy to remove.

[pomatic]

You do not have to remove the battery to disconnect it - the battery plugs in to the motherboard, and can be unplugged with a gentle tug. The battery itself can remain in-situ.

[NullPrefix]

I would assume there's screws that need to be unscrewed to reach that battery plug. Maybe even single use glue.