remove default php mac code example

Example: how to uninstall php from mac catalina completely

$ brew uninstall --force php56 php56-apcu php56-opcache php56-xdebug php56-yaml
$ brew uninstall --force php70 php70-apcu php70-opcache php70-xdebug php70-yaml
$ brew uninstall --force php71 php71-apcu php71-opcache php71-xdebug php71-yaml
$ brew uninstall --force php72 php72-apcu php72-opcache php72-xdebug php72-yaml
$ brew cleanup