This Google Analytics API call https://developers.google.com/apis-explorer/#search/analytics/analytics/v3/analytics.management.uploads.deleteUploadData returns 204 without message body. At least it returns some headers:
cache-control: no-cache, no-store, max-age=0, must-revalidate
date: Tue, 08 Aug 2017 12:44:42 GMT
etag: "sP5LBgqDii7ksJERAgMB0CpTbRM/vyGp6PvFo4RvsFtPoIWeCReyIC8"
expires: Mon, 01 Jan 1990 00:00:00 GMT
pragma: no-cache
server: GSE
vary: Origin, X-Origin
Same behaviour with googleapis@17.1.0 node module.
Edit: As mentioned by m90, this should indicate that the server has fulfilled the request but in my Analytics account no upload items are beeing deleted.