How do I delete the Apple ID from a phone I got from a friend?

you will need to contact the previous owner to have them log out of iCloud or go to https://www.icloud.com/find/ My Phone and erase the device, then remove it from their account. If you can’t do that, the device is useless. 

Turn off Activation Lock - Apple Support.      

I assume the phone is activation locked and that the friend is unavailable to provide the needed password. If I am correct, then the phone will be useless to you. We cannot remove an activation lock. And, you don't have an extenuating circumstance (e.g., you are the original owner of the phone and you have your purchase receipt for the phone with the phone's serial number on it) that would allow Apple Support to remove the activation lock.