You will need to delete everything in the data directory, I don't know where that is as I don't know how graylog installs Elasticsearch. It looks like that would be `/var/lib/elasticsearch`, but you may want to check.

Next time, it's best to use the APIs instead of removing files from the filesystem :)

---
NEW: Monitor These Apps!
elasticsearch, apache solr, apache hbase, hadoop, redis, casssandra, amazon cloudwatch, mysql, memcached, apache kafka, apache zookeeper, apache storm, ubuntu, centOS, red hat, debian, puppet labs, java, senseiDB