As you may know, there is a built-in administrator account whose default name is Administrator in Windows 8 computer. If you want to endow it with a unique name, two commonly-used methods are illustrated below for your reference.
Video guide on how to rename administrator account in Windows 8:
Way 1: Rename administrator account in Computer Management.
Step 1: Open Computer Management.
Step 2: Locate the administrator account.
In Local Users and Groups/Users, you can easily find Administrator.
Step 3: Go to rename it.
You can single-click Administrator, or right-tap Administrator and choose Rename in the context menu.
Step 4: Enter new name.
Type your desired name and the administrator account is renamed successfully.
Way 2: Change administrator name in Local Group Policy Editor.
Step 2: Find and open the policy called "Accounts: Rename administrator account".
BTW, the policy is located in Computer Configuration/Windows Settings/Security Settings/Local Policies/Security Options.
Step 3: In the policy's properties dialog, enter a new name and click OK.
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