To get goxc to publish to bintray, you need a .goxc.local.json with valid API credentials.
The file .goxc.local.json.example provides a template for this.
To delete previous versions on bintray:
$ for v in ..; do http --auth USER:APIKEY DELETE https://api.bintray.com/packages/relops/rmq/rmq/versions/0.2.$v; done