No admin account of Mac

Hi,

There should be another account then, an admin account. Log in to that > System Preferences > Users & Groups > click the lock and enter password > click on your account > check the box for "Allow user to admin this computer."

If your account really is the only account on the Mac, try the same process to turn it into an admin account.

If you don't have another admin account, you can restart the Setup Assistant which will create a new admin user. You can use that to fix your account.

Restarting Setup Assistant to create Admi… - Apple Community

You may not need to delete it from the Data volume. Some here have posted that it seems to be linked back to the original location in the System Volume.

You can try to remove it using this command. If you get a file not found, follow the instructions to mount the Data volume and remove it using the commands in the linked User Tip.

rm -i /private/var/db/.AppleSetupDone

You have to open Terminal from the Utilities menu. That’s where you enter the command.