Hi Hari,
.opendistro-alerting-alert-history is a system index and you cannot make changes to this index by default.
To make changes to the index first you need to allow making changes to the system index from the indexer configuration.
Go to
/etc/wazuh-indexer/opensearch.yml
And change plugins.security.system_indices.enabled: to false from true.
Now, restart the indexer.
systemctl restart wazuh-indexer
And run this command to change the replicas number to 0
curl -k -u user:Password -XPUT 'https://indexer-ip:9200/.opendistro-alerting-alert-history-*/_settings' -H 'Content-Type: application/json' -d '{ "index": { "number_of_replicas": "0", "auto_expand_replicas":"false" } }'
Now, revert the changes you have made in the /etc/wazuh-indexer/opensearch.yml