I worked for a shady evil company, and when they illegally fired me, I never ended up returning a laptop - thinkpad running windoze.
Let’s say I wanted to put Win 8 or similar on it so I can play some video games. What would potentially be barriers to doing this? Said evil company is hopefully going out of business soon, and is a clusterfuck anyway, so they might not end up asking for it back.
Step one is to try and access the bios. If you can, you just need a USB stick with your installer for the OS of your choice (Windows? Eew!).
If not, you’ll need to search for information for your laptop model. You might be able to disassemble the case and remove the CMOS battery. Or, might be another trick?
If you can’t get into the BIOS, you might have a bit more difficult road ahead. Then again, I recall back in the day there was a Linux distro that could launch from an .exe inside of Windows; is that still possible, though? I have no idea.
Good luck! And might not hurt to chat up the next autistic nerdy type you come across. 😂