rman not deleting old files

Hi!

Oracle 19.10, but this isn't really version related.

I have lot of old files in the backup directory I want to clean up. But it seems that there is no command to get rman to check for files it doesn't already know about? As far as I understand, crosscheck obsolete just runs through the files it knows about to see which ones are older than the retention policy? And expired just checks if the files it knows about are really there?

So how do I get rman to delete all files in the backup directory that it doesn't need?