As most people will have known this working with a Windows Azure Pack Web Farm lab environment, cleaning up the data can be a pain since the installer refuses to continue if any databases containing Windows Azure Pack Websites v2 data.
You can easily fix this by running these queries:
drop database [Hosting];
drop database [ResourceMetering];
drop login Hosting_FileServer;
drop login Hosting_HostingAdmin;
drop login Hosting_LoadBalancer;
drop login Hosting_Operations;
drop login Hosting_Publisher;
drop login ResourceMetering;
drop login ResourceMetering_Operations;
That should clean up the database server so a new instance of Websites can be installed on that database server.