Turn off two factor authentication

See the following from 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 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.

Are you having any particular problems w/ 2FA with which me might assist?

HIGHLY RECOMMEND that you provide some serious thought as to the selection of your Trusted Numbers. (especially important for “single-iPhone-only” users)

These numbers become CRITICAL if you ever loose access to all of your Trusted Devices.

See more good info in these two articles:

Two-factor authentication for Apple ID - Apple Support

Get a verification code and sign in with two-factor authentication - Apple Support

The short answer is that you can't.