In Windows 10, as in every release since Windows Vista, the built-in Administrator account is disabled. You can enable that account with a couple quick commands, but think twice before you do it.
This account was necessary in the Windows XP era and earlier, but it's not needed in the current Windows design and is disabled by default to reduce the attack surface on a Windows PC. During Setup, the first account you create is a local administrator and can be used for recovery purposes.
If you need to sign on to Windows from Safe Mode or the Recovery Environment, you can use the primary user account, which is a member of the local administrators group. If you unintentionally demote, delete, or disable the last local administrator account, you can sign on in Safe Mode using the disabled Administrator account.
To enable this account, open an elevated Command Prompt window and issue two commands. First, type net user administrator /active:yes and press Enter. Then type net user administrator <Password>, where <Password> is the actual password you want to use for this account.
Because the local Administrator account is a special account, you can't use it for everyday activities in Windows 10. No Windows Store apps will run, for example, and User Account Control is turned off. And although it's possible to work around those restrictions with some unsupported additional commands, the results can be unpalatable. For example, as soon as you attach a Microsoft account, the ability to switch back to a local account disappears.
Bottom line: Yes, you can enable the Administrator account. But you shouldn't.
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Next week: Another Windows 10 tip from Ed Bott