How to turn off two factor authentication?

In most cases you cannot. What is the issue that you have?

If you’re already using two-factor authentication with your Apple Account, you can’t turn it off. If you updated to two-factor authentication inadvertently, you can turn it off within two weeks of enrollment. If you do, your account is less secure and you can’t use features that require a higher level of security.

Two-factor authentication for Apple Account - Apple Support

dcairns61 wrote:

Not being able to turn off this annoying feature is the end of me buying apple...

The tyranny of apple knows no bounds!

What issue are you having? You do know that it only affects when logging into your Apple Account on a new device.

When you sign in to your Apple Account for the first time on a new device or on the web, you need both your password and the six-digit verification code that’s automatically displayed on your trusted devices.

Two-factor authentication for Apple Account - Apple Support

The whole point is to prevent anyone else that knows your Password from gaining access to your account. That is basic security and something everyone should expect. Every banking site I have also uses two-factor authentication for that reason.

The alternative is the old Security Questions. For one, those are easily compromised through Social Engineering and also if you forget them, there is no way to access your account. Resetting your password with two factor authentication is possible by sending the reset link to your Trusted Phone Number which you can change at any time.

Not being able to turn off this annoying feature is the end of me buying apple...

The tyranny of apple knows no bounds!