delete all
http://localhost:8080/solr/core/update/?stream.body=<delete><query>*:*</query></delete>&stream.contentType=text/xml;charset=utf-8&commit=true
delete by id
http://localhost:8080/solr/core/update/?stream.body=<delete><id>123</id></delete>&stream.contentType=text/xml;charset=utf-8&commit=true