Install Linux on a USB stick or live CD. Boot into that OS and do exactly what you did last time.
Unless they have gone into the firmware to prevent booting from anything but the HDD, this will will work and they can’t detect it.
Once you make the changes and boot back into Windows they won’t know either. While the OS is offline their spyware does nothing. Once you boot back into Windows, it can’t run and can’t “call home”.
As someone else said, they will know eventually that something is broken on your computer, that is, no data from your machine and it becomes a stale object. But they may not automatically believe it was intentionally disabled. You’d be surprised how low compliance numbers need to be in order to be satisfactory, and no security or monitoring solution is flaw-free. They may just blame the software. Many low-level IT admins are prone to this assumption in order to avoid spending a lot of time diagnosing the problem.