@Michael Bronson You can try the following approach to completely remove the unwanted host from your ambari Database. 0. Stop ambari-server. # ambari-server stop 1. Please take a fresh ambari DB dump for safety and backup. 2. Now run the following SQL queries inside your ambari DB to delete the unwanted host. Please replace the "unwanted1.host.com" with your unwanted hostname and similarly the "351" with the "host_id" that you want to remove from your Database. delete from execution_command where task_id in (select task_id from host_role_command where host_id in (351)); delete from host_version where host_id in (351); delete from host_role_command where host_id in (351); delete from serviceconfighosts where host_id in (351); delete from hoststate where host_id in (351); delete from kerberos_principal_host WHERE host_id='unwanted1.host.com'; ----> For kerberized Env delete from hosts where host_name in ('unwanted1.host.com'); delete from alert_current where history_id in ( select alert_id from alert_history where host_name in ('unwanted1.host.com')); 3. Now restart ambari-server. # ambari-server start . ... View more