Turn off two factor authentication

Within two weeks’ having enabled it, see the mail message received when two factor authentication was first enabled.

For an Apple ID that had two-factor authentication enabled when the account was created, or when two-factor has been enabled for more than two weeks, it cannot be disabled.

Based on -> Two-factor authentication for Apple ID

Two-factor authentication for Apple ID - Apple Support

• If you're already using two-factor authentication with your Apple ID, you can't turn it off. If you updated to two-factor authentication inadvertently, you can turn it off within two weeks of enrollment. If you do, your account is less secure and you can't use features that require a higher level of security.

If you have used 2 Factor for more than a couple of weeks, you cannot turn it off. It is an important security feature!