Delete Solr Documents
http://192.168.10.20:8080/solr/update?stream.body="<delete><query>*:*</query></delete>"&commit=true
curl http://192.168.10.20:8080/solr/update -H "Content-Type: text/xml" --data-binary '<delete><query>*:*</query></delete>'
http://192.168.10.20:8080/solr/update?stream.body=<delete><query>id:12345</query><query>username:Daniele</query></delete>&commit=true```
curl http://192.168.10.20:8080/solr/update -H "Content-Type: text/xml" --data-binary '<delete><query>id:12345</query><query>username:Daniele</query></delete>'