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#11
I think if one is really stuck, option 2 above is the way to go: that tells you to enable the built-in real administrator account:
Enable or Disable Elevated Administrator account in Windows 10
In your case I think you would need option 5: this requires you to be able to boot from a recovery drive or a W10 installation USB. If you don't have either of those, then option 6 here
Boot to Advanced Startup Options in Windows 10
is the next alternative.
You really have to try everything!