How to take off passcode from a iPhone to another

I'll start with saying that is not a good idea. Apple's mobile devices are designed to be single user only, with a few exceptions such as helping another person find a missing device. If another person signs in on your device and you don't erase it first, you may end up getting some of their content onto your account and vice-versa. In addition, it may give them ownership of your device unless they are careful to sign out again afterward.

If he has a specific reason for wanting to use your device then perhaps tell us what that is and we can provide advice as to the best way to let him do what he needs.

Hillbilly55 wrote:

im trying to help my son sign in to his iCloud using my iPhone

That’s going to want to merge everything iCloud together, and it’ll be substantial effort to clean up and un-merge it all.

If the passcode of an iPhone has been forgotten, merging your environments will both add substantial work to un-merge, and won’t resolve the forgotten passcode.

I’m going to infer there are no backups for the iPhone with the forgotten passcode, which means the data is inaccessible, and will remain so. Resetting the passcode will reset the iPhone contents. That data is what the passcode protects, and what it encrypts.

And one of the very few ways to mark data as valuable is with backups. No backups, no recovery.

You’re headed for a passcode reset here: If you forgot your iPhone passcode - Apple Support

And for a discussion about backups and data preservation, and possibly also of longer-term data archiving.

Having iCloud access won’t change any of this, as the passcode is not stored anywhere; not on the iPhone, and not on iCloud. And the passcode reset will clear all.