How can I disable two-step verification?

Two-step verification for Apple ID - Apple Support

Refer to the section: "How do I turn off two-step verification?

Sign in to your Apple ID account page.

In the Security section, Click Edit.

Click Turn Off two-step verification.

Create new security questions and verify your date of birth.

You'll get an email confirming that two-step verification for your Apple ID is off.

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By the way, do you really mean the old security method, "two step"?

Two-step verification for Apple ID; click here --> Two-step verification for Apple ID - Apple Support

See the section "How do I turn off two-step verification?

If instead you mean the current two factor authentication, two-factor authentication is enabled by default on new Apple IDs and cannot be turned off. If you have an old account and recently activated Two Factor Authentication note this section of an Apple support article:

"Two-factor authentication for Apple ID" --> Two-factor authentication for Apple ID - Apple Support

--> "Can I turn off two-factor authentication after I’ve turned it on?

... 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 ..."