Nope! I don't get "OK" when I first turn on my 6s Plus. Show a screenshot of it.
FOUND IT! You get the OK button if you use letters in your passcode. I use all digits. No ok button. So if you don't want the ok button, you'll need to change your passcode to either a 4 or 6 digit. All numbers. http://www.iphonefaq.org/archives/972802