remove two factor authentication 2009 macbook pro 3/5

2-factor authentication cannot be removed unless within 2 weeks of creating an account:

Two-factor authentication for Apple ID - Apple Support

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

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."

2 Factor authentication applies to your Apple ID, not a specific device.

The Apple ID being used requires 2 factor authentication.

Did you enter your Apple ID for the install?

If not, the previous owner did not properly prepare the machine for sale.