disable TWO-FACTOR AUTHENTICATION

It can only be turned off if you enabled it within the last two weeks, and to do that you use the enrolment email that you got when you enabled it : Two-factor authentication for Apple ID - Apple Support

If you already use two-factor authentication, you can no longer turn it off. Certain features in the latest versions of iOS and macOS require this extra level of security, which is designed to protect your information. If you recently updated your account, you can unenroll for two weeks. 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.

sujeew wrote:

i need to disable TWO-FACTOR AUTHENTICATION on my apple iphone 7 plus.

Why do you think you need to disable it? Perhaps if you explained the problem, someone could help you find another way to do what you need to do.