User name in File Explorer is wrong - Can I change it?

I have just set up my new ASUS Zenbook laptop. Before I switched it on I switched of my router so there was no internet connection. I thought this would allow me to set up Windows without registering it in my Microsoft account. This worked in November when I set up my GMKtec device for the first time but the ASUS setup process would not let me continue without an internet connection. There was no option to continue so I had to switch on my router. This forced me to sign in to my Microsoft account and during the process I was asked for a user name. I must have typed in ‘wigan’ instead of ‘Ken’, but I didn’t notice at the time. After the setup was complete I signed out of my MS account and changed to a Local account where I was asked for a user name and I used ’Ken’. Unfortunately when I see my user name in File Explorer I see my user name is ‘wigan’ and I am unable to change it in File Explorer. Can anyone tell me how to change ‘wigan’ to ‘Ken’ please?