sudo apt-get purge `dpkg -l | grep php| awk '{print $2}' |tr "\n" " "`

How it works:

First, a list of packages is generated using this series of commands: dpkg -l | grep php| awk '{print $2}' |tr "\n" " ". You can run this part of the command to see what packages would get removed.

Second, when you run the full command, this list of packages gets passed to sudo apt-get purge, removing all that packages.

https://askubuntu.com/questions/59886/how-to-completely-remove-php.