That is the Purchased screen, and when you click on "Not on This Phone" it shows all Apps (or Music if you click the Music option, etc.) in your App Purchase/Download history. You can Hide the apps, but you cannot delete them from your Purchase/Download history:
Hide and unhide purchases in iTunes or iBooks on your Mac or PC - Apple Support
You have to do this in iTunes on a computer. When you get to the screen that displays the apps, you will not see the "x" in the upper left-hand corner of the app, but if you hover over it with your mouse, and then click, it will hide it.
Cheers,
GB