Hi Andrew,
Nice to meet you! My name is Randy and I'm an independent advisor.
If your Wi-Fi keeps turning back on after you manually disable it, try these fixes: first, open your Wi-Fi network’s properties and turn off options like Connect automatically when in range or after restart, next, in Device Manager > Network adapters > your Wi-Fi adapter > Properties > Power Management, uncheck Allow the computer to turn off this device to save power; finally, disable Fast Startup in Control Panel > Power Options > Choose what the power buttons do so background services don’t re-enable Wi-Fi.
Kind regards,