How can I change my Windows 10 user name?

I am setting up a new PC with Windows 10 Pro and I mistakenly logged in with my Microsoft Account. That set me up with an administrator account with a user name made up of the first 5 characters of my email address. But my old PC has a user name which is my first name. I have several file handling utilities that rely on a directory structure of C:/User/, where is my first name. I’ve tried googling and tried several suggestions, but none lead to a place to actually change the name. I did find one way to rename my user name on my MS account site, except that it changes my email address as well. I’m thinking that I have to run Refresh to install Windows again so that I can bypass the log in to Microsoft and create a local account. But a Refresh saves my settings, does that include my account and user name? Or am I asked to do that again so that I can skip it this time.? Is a Refresh a viable way? It won’t be too hard, I’ve only installed a few apps and I can do those over again. Does a refresh change the vendor’s drivers? I’m at a loss. Thanks for any help.