Migration dilemma

A long time ago I started migrating from "classic"/desktop CC to cloud-based CC. I do not remember what happened, but it didn't go right. So I just stayed with the desktop app.

Now I am revisiting it. Basically: I do NOT trust the catalog that migrated/partially migrated before. It doesn't resemble at all what it should resemble, i.e., in the desktop version. I don't know why.

I would like to migrated it again, starting over. That's not allowed. I tried to rename the catalog files to see if that would work, but it doesn't: clearly LR realizes it is the same catalog, renamed.

Any idea how I can start this over?