Cannot delete document because of update conflict

Deleting a doc which has other revisions is done:
curl -X DELETE http://couchhost:5984/couchdb/docid\?rev\=rev_number

This helped me when getting
{"error":"conflict","reason":"Document update conflict."}

First, since your code looks correct as is, check that your params are in fact being sent.

Otherwise, you should check if a revision is marked as deleted:

curl -X GET http://127.0.0.1:5984/kina/  \
 04ce1239166b841ae8a317897ec45b11?revs_info=true
{
  "_id":"04ce1239166b841ae8a317897ec45b11",
  "_rev":"3-bc27b6930ca514527d8954c7c43e6a09",
  "_revs_info":
  [
   {
    "rev":"3-bc27b6930ca514527d8954c7c43e6a09",
    "status":"available"
   },
   {
    "rev":"2-eec205a9d413992850a6e32678485900",
    "status":"deleted"
   },
   {
    "rev":"1-967a00dff5e02add41819138abb3284d",
    "status":"available"
   }
  ]
}

To get rid of the deleted versions, you have to use _purge. For example:

curl -X POST http://127.0.0.1:5984/kina/_purge/ \
     -H "content-type:application/json" \
     -d ’{"7341477ce373f9cc76f351e598001cdd":
           ["2-5c7fb5dfeaf6f7cea149922fa1cdaf96"]
        }’

{
  "purge_seq":1,"purged":
  {
    "7341477ce373f9cc76f351e598001cdd":
    ["2-5c7fb5dfeaf6f7cea149922fa1cdaf96"]
  }
}