To make the Quick Type suggestions go away temporarily, simply place your finger on the gray bar and swipe it down. Should you want to restore it? Just drag the gray bar back up.
You can also press and hold the keyboard icon (the smiley face to the left of the microphone icon) at the bottom-left of your keyboard. This brings up a shortcut to toggle predictive text on and off.
Last Option 3
Alternatively, you can head to your iPhone’s Settings menu. Tap on “General,” then “Keyboard” to see the full options for your iOS keyboard, and turn predictive text off.