How to permanently delete passcode

Why would you even want to do that? Not having a passcode on your iPhone means that ANYONE who might come in contact with it, will have full access to ALL of your data. Your banking apps. Your Photos. Your messages, etc. People come here every day whose phone was lost or stolen. Do you want to be compromised in such a way, when simply using a passcode protects you and your data?

Are possibly thinking that "deleting" the passcode will allow you to access the data on a phone whose Passcode you have forgotten? That plan will not work, since you must know the Passcode to get into the Settings on the phone in order to turn off the requirement to enter a Passcode.

If you do know the Passcode, I am not recommending that you turn it off, but if you really want to do this and understand the consequences, here is how to turn the Passcode requirement off.

Tap Settings

Tap Face ID & Passcode

Tap Turn Passcode Off and follow the prompts

Now anyone who picks up your phone will have complete open access to all the personal data on your phone.