[Ruby] Remove all gems

Using gem command

gem uninstall --all

Using batch file

ruby -e "`gem list`.split(/$/).each { |line| puts `gem uninstall -Iax #{line.split(' ')[0]}` unless line.empty? }"

References

1. https://stackoverflow.com/questions/6373160/how-to-uninstall-all-ruby-gems-on-windows