If you are using an iPhone 6 or iPhone 6 Plus, you must have noticed that tapping on the Touch ID twice brings the top of the display to half of the screen allowing you to access the top controls with just one hand. This is rather useful for apps such as Twitter, where for example you may want to retweet the tweet that is on the top, but on other occasions it can be a bit of a pain. Just an instance, the other day, I was trying to complete an authentication for a payment on the App Store and while the Touch ID did not recognise my finger print for it, it kept minimising the display which was a major annoyance.
And given that the iPhone 6 I use is anyway big enough and wide enough for me to not be able to use it with a single hand, the use of Reachability has been fairly limited. And if just like me, you do not use the feature and it is more of an annoyance than something you would want to use, you can disable the feature easily.
In order to disable Reachability, you can follow the steps below which would do the same:
Go to the Settings apps from the springboard of your iPhone 6 or 6 Plus running iOS 8.
In Settings, click on General, which is in the third set of settings.
Scroll down in General, and find Accessibility and click on it.
When you are in Accessibility, go all the way down and you will find the option of Reachability towards the end of the list and you will see it is enabled by default. Turn it off by flicking the switch and then you see that double tapping the Touch ID will not bring the display half way down.
You can obviously turn Reachability on once again by going through the same steps and tapping on the switch of Reachability back on.