Delete all documents in a collection

If you have enabled Ranger for authorization, you must have Solr Admin permission to be able to delete documents in a collection.

Deleting all documents in a Solr collection does not delete the collection or its configuration files. It only deletes the index. This can be useful for rapid prototyping of configuration changes in test environments.

If you are using Kerberos, kinit as a user with permission to delete the collection:
```
kinit solradmin@EXAMPLE.COM
```
Replace EXAMPLE.COM with your Kerberos realm name.
On a host running Solr Server, make sure that the SOLR_ZK_ENSEMBLE environment variable is set in /etc/solr/conf/solr-env.sh. For example:
```
$ cat /etc/solr/conf/solr-env.sh
export SOLR_ZK_ENSEMBLE=zk01.example.com:2181,zk02.example.com:2181,zk03.example.com:2181/solr
```
If you are using Cloudera Manager, this is automatically set on hosts with a Solr Server or Gateway role.
Delete the documents:
```
solrctl collection --deletedocs logs
```