If you need to deactivate a product key, you can do so by following these steps:
1. Open the Microsoft Store app on your Windows 10 device.
2. Select the profile icon in the top-right corner of the screen.
3. Select "Settings" from the drop-down menu.
4. In the "Settings" window, scroll down to the "Product Keys" section and select "Deactivate product key."
5. Enter the product key you wish to deactivate and select "Deactivate."
6. Confirm that you wish to deactivate the product key by selecting "Deactivate" again.
After following these steps, the product key will be deactivated and you will no longer be able to use it to activate Windows 10.