It looks like these features used to be supported in the old 1.0 API, but are now deprecated. I tried to use them like the still supported groups and I received an error:
{"message": "Resource not found", "detail": "There is no API hosted at this URL.\n\nFor information about our API's, please refer to the documentation at: https://developer.atlassian.com/bitbucket/api/2/reference/"} I don't see any features on the 2.0 API that correlate to creation/deletion of users, or how to view what groups/roles a user has access to.
Any help would be greatly appreciated.