I signed up to be part of the public beta on my iPhone 6 Plus. I then gave my phone to my husband and restored it to factory settings, removed iCloud ac etc and he set it up as his phone. Every time he wakes the phone up he gets a pop up box on screen saying "A new iOS update is available. Please update from the beta". Can anyone advise on how to get rid of this? He's not part of the beta programme.