how to turn off two-factor authentication iphone

Hello,

I see you want to disable two-factor authentication. For some background I suggest you read the document: "Two-factor authentication for Apple ID" - Two-factor authentication for Apple ID - Apple Support

When presented with isolated quotations from that document it is easy to misunderstand if you can or cannot disable two-factor authentication. This is how it works:

Several years ago Apple transitioned to using two-factor authentication for additional account security. Accounts created since that time automatically use two-factor authentication and this cannot be disabled.

Some people have older accounts from before two-factor authentication was mandatory on new accounts. Apple encourages those users to transition to two-factor authentication when signing in on their accounts because without it "your account is less secure and you can't use features that require a higher level of security." Those older account owners who do start using two-factor authentication have two weeks to change their minds and return to older security settings.

If you did indeed recently activate two factor authentication and want to disable it, you should check for an email from Apple. If you don't see one about this, look in your junk mail folder.

If you do not want to receive notices on a particular device I do not think there is a way to configure that other than to remove the Apple ID from the device.