This post is about how to create a custom user profile name (instead of the first 5 characters from your Microsoft Account name) and how to delete the existing profiles, which is needed if you previously created a profile using your Microsoft Account and now want to delete that profile.
Creating a custom user profile name. If you setting the system for the first time, you just need to choose the desired account name. The setup process will create the profile name (and C:\Users\ProfileName ) exactly as you specified.
Otherwise you will need to add a new account. To do this you have to use some existing Administrator account and not the one you are trying to delete (you can create a temporary one and delete it later if needed).
Now if you already messed up with profile name (when trying to create account by signing up with your Microsoft Account and getting profile name as the first 5 characters from your Microsoft Account name), then you need to delete that existing account first, otherwise you will get Another user on this device uses this Microsoft account, so you can’t add it here error when trying to sign in with Microsoft Account.
Use a key combination Windows + Break to open System properties.
Go to Advanced system settings > Advanced tab > User Settings > Settings
Select and delete your old profile (the one with the first 5 characters from your MS account name)
Click Start menu and search for “Computer Management”. Open it from the found
Under Local Users and Groups > Users, delete that user account too.
Then you can also delete the old profile folder: C:\Users\ProfileName
Finally you can create a new account.
Go to Settings > Accounts > Family & Other People.
Click Add someone else to this PC.
On the “How will this person sign in?” page, click I don’t have this person’s sign-in information.
On the “Let’s create your user account” page, click Add a user without a Microsoft account.
Enter a local username that matches exactly what you want to see as the profile name. (If you include a space in the username, the profile folder name will also include a space.)
Add a password and a password hint and finish creating the account.
You can now sign out and sign back in using the new local account. After you sign in, go to Settings > Accounts > Your Info and choose Sign in with a Microsoft account instead. After you finish, your user profile will still have the full name you created when you set up the local account.