I want to stop my upgrade

Why?

What upgrade are doing? It certainly can't be iOS because a Mac is incapable of executing that.

Did you backup prior to starting the upgrade?

A hint would be nice. Which upgrade?

Writing an effective Apple Support Communities question

See: Downgrade your iCloud storage - Apple Support

I guess you solved it. 😎

With that kind of a reply, I am out of here. I don't have to take your abuse.

It is as far as I am concern. Bye.