The Windows Defender is antispyware software that runs by default with Security Centre. Defender alerts you when spyware or potentially unwanted software attempts to install itself or to run on your computer.
To prevent Defender from scanning for spyware or other potentially unwanted software, turn the utility off.
For this, go to Start > Run menu, enter “regedit” and navigate to the registry path listed below. If the subkey “Windows Defender” does not exist, create it as explained below. Then, create a string value “DisableAntiSpyware” in the right panel, and change the value to “1”.
However, if you want to get Windows Defender back in running mode, delete the subkey “Windows Defender”.
The changes take effect after a restart or logoff.