There is currently no way to delete a tenant (and everything belonging to it) from the system. Data points are automatically purged. If you want to completely remove a tenant from the system, our data purge is not adequate for a couple reasons. First, data purge does not allow you to delete things immediately. Secondly, data purge only removes data points. To completely delete a tenant we also need to update the following tables:
We already have HWKMETRIC-413 open for creating a tool for manually deleting data. My preference would be to do it through the REST API. The endpoint will need to be secured, and that can be handled on a per deployment basis with whatever security mechanisms are available. I already talked about this with Matt Wringe to make sure we can secure this in OpenShift.