Sometimes, you just want to cleanup old ElasticSearch indexes, especially logstash indexes can become quite numerous.
Deleting everything from a certain month:
curl -XDELETE http://127.0.0.1:9200/logstash-2016.6.[1-30]
Or multiple months:
curl -XDELETE http://127.0.0.1:9200/logstash-2016.[1-6].[1-30]