Delete a subtitle on your account. Don't forget to specify DELETE as the request method as GET will call the show action rather than update.
https://streamio.com/api/v1/subtitles/subtitle_id.format
DELETE
200
Just remember to DELETE and you'll be fine.
curl -u username:password \
-X DELETE \
https://streamio.com/api/v1/subtitles/4c48388bbf4b9802c5000007.json