Hi @Stewartd64
Welcome to the HP Support Community. I'd be happy to assist you with the administrator account.
Please try these steps -
1) Under Settings > Accounts > Family & other users, select the account owner name, then select Change account type.
2) Under Account type, select Administrator and OK.
3) Sign in with the new administrator account.
You may also refer to this document - HP PCs - Managing User Accounts and Logins (Windows 10)
Hope this helps! Keep me posted.
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Asmita
I am an HP Employee