After finalizing an upgrade to HDP 2.3.4 the old software is still on the servers in the cluster. I haven't seen anything with Ambari managing the removal of this, so what have others done to manage this (manually delete, yum, etc.)?
Yes you use yum to uninstall. Make sure you remove right packages but if you have plenty of storage for /usr/hdp i usually leave one or two versions behind.