How to remove Elasticsearch node(s)

3 nodes -> 1 node

from Elasticsearch Master node

$ curl -X PUT localhost:9200/_cluster/settings -H 'Content-Type: application/json' -d '{
  "transient" :{
      "cluster.routing.allocation.exclude._ip" : "xxx.xxx.xxx.xxx"
   }
}'

{"acknowledged":true,"persistent":{},"transient":{"cluster":{"routing":{"allocation":{"exclude":{"_ip":"xxx.xxx.xxx.xxx"}}}}}}

shutdown elasticsearch node to be removed

systemctl stop elasticsearch

edit /etc/elasticsearch/elasticsearch.yml

discovery.zen.ping.unicast.hosts
discovery.zen.minimum_master_nodes: 3 -> (none)

/etc/elasticsearch/elasticsearch.yml

# Pass an initial list of hosts to perform discovery when new node is started:
# The default list of hosts is ["127.0.0.1", "[::1]"]
#
#discovery.zen.ping.unicast.hosts: ["host1", "host2"]
#
# Prevent the "split brain" by configuring the majority of nodes (total number of master-eligible nodes / 2 + 1):
#
#discovery.zen.minimum_master_nodes:

set replica = 0 !

curl -XPUT 'localhost:9200/_settings' -H 'Content-Type: application/json' -d '
{
    "index" : {
        "number_of_replicas" : 0
    }
}'

{"acknowledged":true}

then repeat

$ curl -X PUT localhost:9200/_cluster/settings -H 'Content-Type: application/json' -d '{
  "transient" :{
      "cluster.routing.allocation.exclude._ip" : "yyy.yyy.yyy.yyy"
   }
}'

{"acknowledged":true,"persistent":{},"transient":{"cluster":{"routing":{"allocation":{"exclude":{"_ip":"xxx.xxx.xxx.xxx"}}}}}}

shutdown elasticsearch node to be removed

systemctl stop elasticsearch

Reference