How-To: Cleanup SolrCloud entries in ZooKeeper
These instructions assume you don't need to preserve Solr indexes. If you do, modify ZK commands to move nodes instead of removing them.
Stop every SolrCloud node:
# on every SolrCloud node
su - solr
cd /opt/lucidworks-hdpsearch/solr/bin/
./solr stop -all
Connect to your ZooKeeper quorum and run zkCli shell:
su - zookeeper
cd /usr/hdp/current/zookeeper-client/bin/
# point it to a ZK quorum (or just a single ZK server is ok, e.g. localhost)
./zkCli.sh -server lake02:2181,lake03:2181,lake04:2181
If you followed best practices and chroot'ed your SolrCloud already, then things are easy (and you probably are done by now):
# in ZK cli shell
rmr /solr
More often this wasn't the case, so perform the following operations on your ZK tree:
# in ZK cli shell
rmr /clusterstate.json
rmr /aliases.json
rmr /live_nodes
rmr /overseer
rmr /overseer_elect
rmr /collections
Next, follow this best practices article, create a new ZK home for your SolrCloud cluster and start it up in chroot'ed mode.

