Laptop has a new owner: How to change Administrator file locations

Hello, can someone help? I was given a Windows 10 laptop where the previous owner/administrator "John" has, of course, all "my documents" files under c:/users/john/.... (There is no password to start the system, only a "Welcome John" windows and OK button.)
How can I change the system so it greets *me* upon startup, and change administrator name/file location/ so that it reads c:/users/myname/... ?
I know I can add myself as a new user, and give myself administrator access, but then how can I get rid of the /john/ path, files, and welcome window?
I hope the question makes sense. Thanks in advance.

Marzik said:

Hello, can someone help? I was given a Windows 10 laptop where the previous owner/administrator "John" has, of course, all "my documents" files under c:/users/john/.... (There is no password to start the system, only a "Welcome John" windows and OK button.)
How can I change the system so it greets *me* upon startup, and change administrator name/file location/ so that it reads c:/users/myname/... ?
I know I can add myself as a new user, and give myself administrator access, but then how can I get rid of the /john/ path, files, and welcome window?
I hope the question makes sense. Thanks in advance.

First, I recommend the clean install of Windows 10 as well.

But in regards to users:
Add Local Account or Microsoft Account in Windows 10

Change Account Type in Windows 10

Delete User Account in Windows 10