hi, how can i turn off two-factor authentication on my iphone?

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? This section says: 

"If you recently updated your account, you can unenroll within two weeks of enrollment. 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 and means that you can't use features that require higher security."

This quote emphasizes the security-related importance of two-factor authentication. I would not turn it off even if you are able to. Another reason for not turning it off is that if you use two-factor authentication, then you no longer will have a need for security questions. They are turned off when two-factor authentication is activated.

You can try contacting Apple ID Support. See the Apple Support articles below for contact information.  

Apple ID - Official Apple Support.    

Contact Apple for help with Apple ID account security - Apple Support.   (Link doesn’t always load)  

Get Support          Work through the screens to get a chat option. 

Apple Support schedule phone call

https://twitter.com/AppleSupport.          People have posted it may take an hour or more to get a response.

From the Apple Support article below. 

Without proof of your identity via security questions and other carefully selected criteria, Apple Support can't help you reset a password or perform any other actions on your account. These policies are audited and reviewed on a regular basis.

Security and your Apple ID - Apple Support.      

I accidentally turned it on mistaking it for google two step authentication. I never received an enrollment conformation email. How else can I disable it?