how do i reset a forgotten restrictions passcode on iphone 6 newest update

You will have to erase.

If you forgot the passcode [including a restrictions passcode] for your iPhone, iPad, or iPod touch, or your device is disabled - http://support.apple.com/HT204306 - You can restore from a backup but that backup has to date from before you set the restrictions password.

Unfortunately, you will have to erase the device. You can do that by following the steps on this page: If you can't update or restore your iPhone, iPad, or iPod touch - Apple Support. (Remember all content of the device will be wiped from the device so make sure you have a copy of your info)