Как полностью удалить php и composer с Ubuntu 16.04

Хочу удалить php и composer и переустановить через ошибку:

artem@artem-desktop:~/Work/Web-T/CRM$ composer install
Loading composer repositories with package information
Installing dependencies (including require-dev) from lock file
Your requirements could not be resolved to an installable set of 
packages.
Problem 1
- Installation request for squizlabs/php_codesniffer 3.x-dev -> 
satisfiable by squizlabs/php_codesniffer[3.x-dev].
- squizlabs/php_codesniffer 3.x-dev requires ext-simplexml * -> the  
requested PHP extension simplexml is missing from your system.
Problem 2
- Installation request for squizlabs/php_codesniffer dev-master -> 
satisfiable by squizlabs/php_codesniffer[dev-master].
- squizlabs/php_codesniffer dev-master requires ext-simplexml * -> the 
requested PHP extension simplexml is missing from your system.
To enable extensions, verify that they are enabled in your .ini files:
- /etc/php/7.1/cli/php.ini
- /etc/php/7.1/cli/conf.d/10-opcache.ini
- /etc/php/7.1/cli/conf.d/10-pdo.ini
- /etc/php/7.1/cli/conf.d/20-calendar.ini
- /etc/php/7.1/cli/conf.d/20-ctype.ini
- /etc/php/7.1/cli/conf.d/20-exif.ini
- /etc/php/7.1/cli/conf.d/20-fileinfo.ini
- /etc/php/7.1/cli/conf.d/20-ftp.ini
- /etc/php/7.1/cli/conf.d/20-gettext.ini
- /etc/php/7.1/cli/conf.d/20-iconv.ini
- /etc/php/7.1/cli/conf.d/20-json.ini
- /etc/php/7.1/cli/conf.d/20-mbstring.ini
- /etc/php/7.1/cli/conf.d/20-phar.ini
- /etc/php/7.1/cli/conf.d/20-posix.ini
- /etc/php/7.1/cli/conf.d/20-readline.ini
- /etc/php/7.1/cli/conf.d/20-shmop.ini
- /etc/php/7.1/cli/conf.d/20-sockets.ini
- /etc/php/7.1/cli/conf.d/20-sysvmsg.ini
- /etc/php/7.1/cli/conf.d/20-sysvsem.ini
- /etc/php/7.1/cli/conf.d/20-sysvshm.ini
- /etc/php/7.1/cli/conf.d/20-tokenizer.ini
You can also run `php --ini` inside terminal to see which files are 
used by PHP in CLI mode.

Побывал удалять через руководства и команды:

sudo apt-get purge php
sudo apt-get purge composer
sudo apt-get remove php
sudo apt-get remove composer

Не помогает.