my bad, from the sharpness in your answers i figured you used a production machine

(some people do that because of the lack of a test machine)...
Your tip for the never install in a clean enviroment is partially good but not all

if you install in a clean enviroment and it works its ok, if you then install it on a test enviroment with the exact buildup as you production enviroment and it doesnt work, then you know that it is a setting/program somewhere that is messing up since it works in a clean enviroment.
with a virtual enviroment its easy to create an exact copy (at least the most important parts) of the production enviroment when needed.
yes now its more clear what you meant, you see after (miss)understanding each other and discussing things it gets more clear
It would be nice yes if an uninstaller could remove the databases from SBC from SQL server and the SBC management website from IIS without uninstalling the role and features...
Im not sure if SQL 2008 express has different database instances like you can make with the paid server product. So that would mean deleting the databases itself from the running instance (which is actually a viable option, IF the databases are deleted by named deletion and not by a DELETE *

)