Uninstall php 7 in ubuntu 18 04

Question

I have a server with a PHP 5.6-based application running on it. However, I changed the server's operating system from Ubuntu 14.04 to 18.04 and, in the process, upgraded PHP to 7.2. I'm currently attempting to uninstall it, but I'm having trouble. 

I have run the command:

sudo apt-get remove php

and

sudo apt-get remove --purge php

Although it claims that PHP is not installed, when I execute PHP —version, I still see PHP version 7.

PHP 7.2.19-0ubuntu0.18.04.2 (cli) (built: Aug 12 2019 19:34:28) ( NTS ) Copyright (c) 1997-2018 The PHP Group Zend Engine v3.2.0, Copyright (c) 1998-2018 Zend Technologies with Zend OPcache v7.2.19-0ubuntu0.18.04.2, Copyright (c) 1999-2018, by Zend Technologies

Can someone please help me with this?