# http://wiki.apache.org/solr/FAQ#How_can_I_delete_all_documents_from_my_index.3F
# http://wiki.apache.org/solr/UpdateXmlMessages#Updating_a_Data_Record_via_curl
curl "http://index.websolr.com/solr/a0b1c2d3/update?commit=true" -H "Content-Type: text/xml" --data-binary '<delete><query>*:*</query></delete>'
I'm amused at the traction this little gist is getting on Google! I would be remiss not to point out that six+ years later I'm still helping thousands of companies on a daily basis with their search index management, by providing managed Solr as a service over at Websolr, and hosted Elasticsearch at Bonsai. Check us out if you'd like an expert helping hand at Solr and Elasticsearch hosting, ops and support!
Solr version 7.2.0 doesn't allow stream body anymore.
However, SainathSharmadha code will work by using binary data type.
If you're using the Post tool provided by solr:
bin/post -c core_name -type text/xml -out yes -d $'<delete><query>*:*</query></delete>'