how to prep to use odacli cleanup-patchrepo

I have a "newly" re-imaged 19.9 oda. The only system patches applied were for 19.9. In prep for applying 19.10 I find /opt is probably in need of a cleanup. The 19.10 patches are on the order of 19-20G and I only see 17G free. How can I measure what can be removed? I find lots of docs talking about using "odacli cleanup-patchrepo," but I don't know how to determine what would be valid arguments to the command. Doc ID 1681062.1 is very clear on syntax, but very thin on how args were determined. It seems to have much to say about how to use oakcli to study the situation and nothing much on odacli. I suspect some updates are in order here.