bundle remove [GEM [GEM ...]] [--install]
Removes the given gems from the Gemfile while ensuring that the resulting Gemfile is still valid. If a gem cannot be removed, a warning is printed. If a gem is already absent from the Gemfile, and error is raised.
Runs bundle install after the given gems have been removed from the Gemfile, which ensures that both the lockfile and the installed gems on disk are also updated to remove the given gem(s).
bundle remove rails
bundle remove rails rack
bundle remove rails rack --install