post https://example.com/v1/delete
This method deletes an existing submission.
Delete the specified submission
POST /api/v1/delete HTTP/1.1
Host: www.formstack.com
api_key=[[app:api_key]]&id=10001
curl -X POST -i -d "api_key=[[app:api_key]]&id=10001" https://www.formstack.com/api/v1/delete