Use the following instruction to decommission HBase RegionServers in your cluster.

At the RegionServer that you want to decommission, execute:

su <HBASE_USER>
/usr/hdp/current/hbase-client/bin/hbase-daemon.sh <RegionServer.Hostname>

where <HBASE_USER> is the user who owns the HBase Services. For example, hbase.

RegionServer closes all the regions, then shuts down.