Just for anyone wondering,
FInd Winapp2.ini in the Ccleaner directory, open it, find a nice spot to add the following lines:
[spotify]
LangSecref=3023
Detect=HKCU\Software\Spotify
Default=false
FileKey1=%LocalAppData%\Spotify\Storage\*.*
Now reopen CCleaner and go to the Cleaner section, click the Applications tab, and enable Spotify. Or skip this step by changing line Default=false to default=true.
Depending on how many files, it could take a bit of extra time as Spotify makes a few dozen 1+ MB files. I had around 920GB worth. Took an extra 30 seconds. Sub sequential scans should take much less.
