title: DROP SERIES with tag key
body: <p>I am using version 1.2.1-c1.2.2 shell version</p>
  
  <p>I wish to drop all series in my database where the tag value is not null.
  <a href="https://docs.influxdata.com/influxdb/v1.3/query_language/database_management/#drop-series-from-the-index-with-drop-series" rel="nofollow noreferrer">https://docs.influxdata.com/influxdb/v1.3/query_language/database_management/#drop-series-from-the-index-with-drop-series</a></p>
  
  <p>I ran the following query but kept getting the same error. How can I drop series using the where clause?</p>
  
  <pre><code>drop series from "measurement" where "tag" != ''
  
  drop series from "measurement" where "tag" != 'abcd'
  </code></pre>
  
  <p>I got the following error</p>
  
  <pre><code>ERR: partial success, node 4 may be down (error code 1: fields not supported in WHERE clause during deletion)
  </code></pre>
  
  <p>How can I drop series using the WHERE clause on a key_value?</p>