I attempted an upgrade of our production server from SQL Server 2008 to SQL Server 2008 R2 a few days ago which encountered some issues and rolled itself back. I attempted to restart the upgrade process again, however when I attempt to upgrade my instance (only the one instance on the machine) it gets to the instance selection point and spits the dummy with the following:
The Instance ID 'MSSQLSERVER' is already in use by SQL server instance 'MSSQLSERVER.INACTIVE'. To conrinue, specify a unique Instance ID
Given the late night and requirement for sleep I abandoned the process after checking that SQL 2008 was running fine and client connectivity was unaffected.

I'm loading up the setup again and when I run the Installed SQL Server Features Discovery Report I see what appears to be the problem:
Sql Server 2008 MSSQLSERVER MSSQL10.MSSQLSERVER Database Engine Services 1033 Standard Edition 10.0.1600.22 No
Sql Server 2008 MSSQLSERVER MSSQL10.MSSQLSERVER SQL Server Replication 1033 Standard Edition 10.0.1600.22 No
Sql Server 2008 MSSQLSERVER MSSQL10.MSSQLSERVER Full-Text Search 1033 Standard Edition 10.0.1600.22 No
Sql Server 2008 MSSQLSERVER MSAS10.MSSQLSERVER Analysis Services 1033 Standard Edition 10.0.1600.22 No
Sql Server 2008 MSSQLSERVER MSRS10.MSSQLSERVER Reporting Services 1033 Standard Edition 10.0.1600.22 No
Microsoft SQL Server 2008 R2 MSSQLSERVER.INACTIVE MSAS10_50.MSSQLSERVER Analysis Services 1033 Standard Edition 10.50.1600.1 No
Now, the bastard won't let me uninstall that last instance of analysis services any which way I try it. If I try via add-remove programs the only feature available for uninstallation is SQL Client connectivity SDK, I've tried via command line with:
Code:
setup.exe /ACTION=uninstall /FEATURES=AS /INSTANCEID=MSAS10_50.MSSQLSERVER /Q
Which just tells me that there was nothing to uninstall.

When I look in the MSAS10.MSSQLSERVER\OLAP directory there's about 80 files in 30 folders, but in the MSAS10_50.MSSQLSERVER\OLAP directory there's only 50 files in 20 folders (in fact only the Bin sub-folder and everything below that exists) so something has already removed most of the files. I'm wondering therefore if I can just blast the relevant registry entries and delete the rest of these files to make things happy.

But of course I'm open to more sane suggestions for getting rid of this orphaned instance if anyone can offer anything up...