When you install Microsoft Windows, you have to enter a product key in order to activate it. The product key is a series of letters or numbers and is provided with your computer or the Windows software. There are applications that will delete the Windows key, but you can do so by entering a simple DOS command.
Step 1: Click on the Start.
Step 2: Type
cmd in the Search box, and then press on the Enter key.
Step 3: Type
slmgr --cpky and press on the Enter key. Wait for confirmation.
Step 4: Restart the computer.
Into Windows: Delete Windows Product Key from Registry