remove 命令
remove 命令用于移除一个包及其依赖（在依赖没有被其他包使用的情况下），如果依赖被其他包使用，则无法移除：
$ composer remove monolog/monolog
Loading composer repositories with package information
Updating dependencies (including require-dev)
Package operations: 0 installs, 0 updates, 2 removals
- Removing psr/log (1.0.2)
- Removing monolog/monolog (1.23.0)
Generating autoload files