Hello, this is Emily.
Because your onboard license is for Windows 10 Home, you cannot just deactivate the license because then your Pro is still not activated after that. You need to go back to Home. The only way to go from Pro to Home is clean install. I am sorry but you need to backup you personal data, and then perform this clean install.
To perform a clean installation of Windows 10 using the Windows Media Creation Tool.
The following steps should be done on a working Windows computer:
Download the Windows Media Creation Tool from Microsoft's official website. https://www.microsoft.com/software-download/win...
Run the tool and select "Create installation media for another PC."
Choose your language, edition, and architecture (32 or 64-bit) and select "Next."
Choose "USB flash drive" as the media to use for the installation and select "Next."
Connect a USB flash drive with at least 8 GB of free space to your computer.
Select the USB flash drive you want to use, and then select "Next."
The tool will then download the required files and create the installation media.
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Now these steps will be done on your problematic computer:
Go to the computer's BIOS boot menu to have it boot from the USB drive.
Follow the on-screen instructions to install Windows 10, making sure to choose "Custom install" and select the option to delete all existing partitions.
Once the installation is complete, you'll have a clean installation of Windows 10 on your computer.