How do I remove PHP 7 Completely?

To remove php7.0 use

sudo apt-get purge php7.0-common

This will remove all php7 version, be it php 7.0 or php 7.1 etc..

sudo apt-get purge php7.*

As I have answered your question Unable to locate package php7.0 and you have accepted my answer and because you explicitly ask for a removal of the package:

sudo apt-get install ppa-purge
sudo ppa-purge ppa:ondrej/php-7.0