Logstash to delete document from Elasticsearch

No, there is no activity on the ES logs.. I constantly see this error when I run logstash again after deleting the .since_db files.. and running logstash again to parse the files..

Got error to send bulk of actions: [500] {"error":"IllegalArgumentException[Malformed action/metadata line [2], expected START_OBJECT or END_OBJECT but found [VALUE_STRING]]","status":500} {:level=>:error}
Failed to flush outgoing items {:outgoing_count=>81, :exception=>"Elasticsearch::Transport::Transport::Errors::InternalServerError", :backtrace=>["/opt/logstash/vendor/bundle/jruby/1.9/gems/elasticsearch-transport-1.0.12/lib/elasticsearch/transport/transport/base.rb:135:in __raise_transport_error'", "/opt/logstash/vendor/bundle/jruby/1.9/gems/elasticsearch-transport-1.0.12/lib/elasticsearch/transport/transport/base.rb:227:inperform_request'", "/opt/logstash/vendor/bundle/jruby/1.9/gems/elasticsearch-transport-1.0.12/lib/elasticsearch/transport/transport/http/manticore.rb:54:in perform_request'", "/opt/logstash/vendor/bundle/jruby/1.9/gems/elasticsearch-transport-1.0.12/lib/elasticsearch/transport/client.rb:119:inperform_request'", "/opt/logstash/vendor/bundle/jruby/1.9/gems/elasticsearch-api-1.0.12/lib/elasticsearch/api/actions/bulk.rb:80:in bulk'", "/opt/logstash/vendor/bundle/jruby/1.9/gems/logstash-output-elasticsearch-1.0.7-java/lib/logstash/outputs/elasticsearch/protocol.rb:104:inbulk'", "/opt/logstash/vendor/bundle/jruby/1.9/gems/logstash-output-elasticsearch-1.0.7-java/lib/logstash/outputs/elasticsearch.rb:542:in submit'", "/opt/logstash/vendor/bundle/jruby/1.9/gems/logstash-output-elasticsearch-1.0.7-java/lib/logstash/outputs/elasticsearch.rb:566:inflush'", "/opt/logstash/vendor/bundle/jruby/1.9/gems/stud-0.0.21/lib/stud/buffer.rb:219:in buffer_flush'", "org/jruby/RubyHash.java:1341:ineach'", "/opt/logstash/vendor/bundle/jruby/1.9/gems/stud-0.0.21/lib/stud/buffer.rb:216:in buffer_flush'", "/opt/logstash/vendor/bundle/jruby/1.9/gems/stud-0.0.21/lib/stud/buffer.rb:193:inbuffer_flush'", "/opt/logstash/vendor/bundle/jruby/1.9/gems/stud-0.0.21/lib/stud/buffer.rb:112:in buffer_initialize'", "org/jruby/RubyKernel.java:1511:inloop'", "/opt/logstash/vendor/bundle/jruby/1.9/gems/stud-0.0.21/lib/stud/buffer.rb:110:in `buffer_initialize'"], :level=>:warn}

This started happening when I added "delete" in my configuration. Please let me know the best way to delete a record from ES using logstash config.

Thanks.