How do I turn off 2 factor authentication? Having a 6 digit code sent to my iPhone which makes find my iPhone useless

How do I turn off 2 factor authentication? I only have 1 APPLE device my phone. One of the best features of Apple is the find my iPhone. Yet it now requires me to use a 6 digit code which is sent to my iPhone which makes find my iPhone completely useless. Can I add another family member's phone # or an email to receive the code?