Can't disable two-factor authentication?

For some reason, a while ago, whenever I log into the iTunes Store on Windows, it tells me I have to check my iPad or iPod (iOS device) for a security code... which pops up a Location window asking me if it's OK to authorize the device (which it never remembers), then pops up a code I have to type into my Windows iTunes pop-up to just even redeem a gift certificate (the browser URL opens iTunes).

When I follow the instructions to turn off two-factor authentication - https://support.apple.com/en-us/HT204915 - there's NO option in my Security settings to do this... it just says it's ON, even after I've clicked Edit and can edit anything else. On my iOS device, there's also no option to turn it off as the instructions say.

What is going on? It's a giant PAIN to have to keep running around the place to grab my iPad or iPod, fish it out of a backpack, pull it off a dock, jump through all these hoops to just do a simple thing on my iTunes for Windows. It REALLY makes me not want to go to the iTunes Store, AT ALL. My Windows device is already locked by a password that nobody else knows, and I lock it every time I get up.

The way Apple is doing 2FA is nonsense here, their devices and my account is just not that special, I feel like I'm working for the NSA or something. I don't need this, I've only ever used it for something like cryptocurrency, and if people had to do this for every account, they'd go crazy and not want to use their accounts.