1. Open Windows Defender.
2. Click on Tools > Options > Administrator options.
3. Uncheck Windows Defender and Save.
4. Click Continue if UAC prompt.

1. Go to Run (Win Key + R), type in Services.msc, click OK.
2. Now here look for Windows Defender service, right click and click on Properties.
3. Set the Startup at Disabled and click on Stop button and apply.
4. After this is done to go Run again and type Msconfig, click OK.
5. Go to startup tab and uncheck Windows Defender and apply.

Note : At certain places the UAC will ask you permission to continue, just click on continue to
proceed. You also need to disable Windows Defender at msconfig once you
have done at stoped and disabled from services. If you fail to do so it
will give you a error message.