I want to turn off two step authentification

Generally, you cannot. If you have an older Apple ID, and two-factor authentication has been active for less than two weeks, you may be able to turn it off and make your account less secure, but you'll also lose access to services that require two-factor authentication. https://support.apple.com/en-us/HT204915

Newer Apple IDs have 2FA on by default and it cannot be turned off.

Kavanab wrote:

I don't want to have two-step authentication on my Mac. How do I turn it off

What is the issue...where?

two-step authentication is basic security feature that should benefit you not impede you...

ref:

Two-factor authentication for Apple ID

Use two-factor authentication for security on your Mac, iOS ...

Availability of two-factor authentication for Apple ID

Manage two-factor authentication for your Apple ID from iPhone