Let's see, there are many questions here.

Yes, you are in the right place.

Did you get the upgrade price? You should have, if you purchased through PG Music, who keeps records. BIAB during install does not check for the presence of an existing installation. More on this, below.

Why was your old program in /program files/cc? I think you might have meant to type bb instead of cc, but in any event, BIAB defaults to /bb under the root, as you found out, but you can override that and put it anywhere you want. It is likely you did so for the old version. We have found, from Vista and Windows 7, that Windows is more particular now about placing files into the /program files folder, with user account control, but it is possible.

Yes, you can safely delete your old 'cc' folder, because the new one does not need it. The only reason you might not want to do that is that sometimes BIAB offers add-on paks, and if you had anything from those from before and needed them, you would lose them in the new installation. For years (decades?), many of us just install the new version right on top of the old, with no problem, because we then keep everything. You could still do that, and then delete the first 'new' 2010 installation you just did.

You will not find an 'uninstall' program for BIAB, as it does not write to the Registry and can simply be deleted by deleting the whole /bb folder.

Realband did not exist in 2006, so that one can also go wherever you want.

BIAB 2025 Win Audiophile. Software: Studio One 7 Pro, Swam horns, Acoustica-7, Notion 6, Song Master Pro, Win 11 Home. Hardware: Intel i9, 32 Gb; Roland Integra-7, Presonus 192 & Faderport 8, Royer 121, Adam Sub8 & Neumann 120 monitors.