Hi Sanford Harty,
When you select “work/school use” during the initial setup, Windows automatically configures the device to expect an organizational account, which is why you’re now being blocked from admin-level changes. Since you don’t have a work or school account, the simplest way to reset the devices back to personal use is to perform a full reset and choose “set up for personal use” during the out-of-box experience (OOBE).
To do this, go to Settings > System > Recovery > Reset this PC, and select the option to remove everything. This will reinstall Windows and allow you to go through setup again. When prompted, make sure to select “personal use” and sign in with your Microsoft account (or create one if needed). That account will then be the administrator account for the device, giving you full control to install software and make changes.
If you’d prefer not to reset, you can also create a new local administrator account from the recovery environment, but the reset path is usually cleaner and avoids lingering configuration issues.
I hope the response provided some helpful insight. If you find this answer useful, please hit “accept answer” so I know it addressed your concern.
Jason.