Erase/Reset iCloud Keychain - 'Factory reset' AppleID - maintain purchases and iCloud storage

There is information in my iCloud Keychain and possibly iCloud backups that carries over when I wipe/erase/DFU restore my Macbook's and my iPhone.

I want to essentially erase my keychain and have a new one within iCloud - removing all old stale/malicious information stored within. There doesn't seem to be an easy way to do this.

Going through the hoops defined online - going through settings - appleID - iCloud - keychain, the toggle locks up settings - never 'works' and forces me to sign back into iCloud on my MacBooks. Also - keychain access - settings - reset default keychains doesn't seem to do what I'm after. It creates a new local keychain, when I want the iCloud one erased. No matter what I do - eventually what's in iCloud is brought into my local keychain. To delete manually would be cumbersome, I could delete things that I shouldn't.

I can't clear things out - I'm totally stuck. After DFU restoring a Macbook, it seems fine until I sign in with my appleID - want whatever is in there cleared out - essentially 'factory resetting' my appleID - while maintaining purchases and iCloud storage.