pass codes
how can i remove the passcode from a iphone 6, my 93 year old grandfather has a iphone last week over the holidays he lost his phone, So I logged into his Icloud account and listed the phone as lost with the message to call me. He found that he left the phone at his dr office so I showed it as found and it opened back up fine...except now it has a passcode and its infuriating him to no end. Please can anyone give me simple straightforward directions to remove this passcode from his phone.
thank you!
iPhone 6, iOS 12