TWO-FACTOR AUTHENTICATION

You may not be able to turn it off (see below). Your Apple ID account would be the place to do so using a computer under Windows if you qualify. What is the problem when you try to. turn it off--assuming you are within the two-week period mentioned below?

See Two-factor authentication for Apple ID https://support.apple.com/en-us/HT204915 and more specifically the section entitled Can I turn off two-factor authentication after I’ve turned it on? You can't turn it off unless you recently updated your account. In this case, you can unenroll within two weeks of enrollment.

If you are in the two-week period, "Just open your enrollment confirmation email and click the link to return to your previous security settings. Keep in mind, this makes your account less secure."

After two weeks, no, two-factor authentication cannot be disabled.

With no trusted devices, you’ll need to use trusted telephone numbers, described here:

Two-factor authentication for Apple ID - Apple Support

When past two weeks, and with no trusted devices, and no trusted telephone numbers:

Recover your Apple ID when you can’t reset your password - Apple Support