activate iphone 6s

Unless the previous owner removes their Apple ID from this phone, you will not be able to activate it, and it will be useless to you. There is nothing anyone here, nor Apple, can do to assist you with this.

If the previous owner does not remember their password, have them review the following article:

• If you forgot your Apple ID password - Apple Support

After they recover it, then have them follow the directions in this article to prepare the phone for a new owner:

• What to do before you sell, give away, or trade in your iPhone, iPad, or iPod Touch - Apple Support

The previous owner needs to do this: https://support.apple.com/en-us/HT201351

~Lyssa