Two factor authentication code

As long as you have any Apple trusted device listed under your AppleID you can receive 2FA codes, be it an iPad, an iPod touch, or a Mac. 2FA codes, by default, are sent to your trusted devices as encrypted iCloud notifications, so they do not need an iPhone to be received.

You cannot remove two factor authentication when you have enabled it before.

This is for safety and security reasons.

See this link for further reference Two-factor authentication for Apple ID – Apple Support (UK)