There is way to enable Windows build in Administrator account and when you do you can add your user account to Administrators group from Control Panel --> User Accounts --> Manage Another Accounts click your user account and click Change the account type.
To enable Windows build in Administrator account follow my instructions at How to Enable Windows Build-in Administrator Account section. Make sure to backup the SAM registry hive just in case you have trouble following my instructions and make changes you don't want you can restore the SAM hive with SAM hive you have backup before modifying the SAM registry hive.
You can completely backup registry hive by copying to a another location you need to open the Command Prompt then type below command:
Copy C:\Windows\System32\Config\SAM C:\
Above command copies the SAM hive store within C:\Windows\System32\Config folder to root of the C: partition.
When computer boots into Windows Recovery Environment (WinRE) environment the drive letter assign to Windows partition may not be C: drive letter because Windows 7, 8 , 8.1 and 10 creates a separate system partition when it's installed from scratch. The system partition contains boot files WinRE assigns the system partition the C: drive letter and the Windows installed partition will be assign any other drive letter usually D: drive letter is assign to Windows installed partition. The Bcdedit /enum | find "osdevice" command can be use to find out the drive letter of the Windows installed partition the output of the Bcdedit command is similar to this osdevice partition=D:. The drive letter after partition= is the drive letter of the Windows partition.