Windows Defender is the the default antivirus application of Windows 10. Older versions of Windows, such as Windows 8.1, Windows 8, Windows 7. Vista also had the app, but was less effective at the time as it only looked for spyware and adware.
In Windows 8 and Windows 10, Defender is application-based Microsoft Security Essentials, which offers better protection by adding complete protection against all kinds of malware programs. 
However, if you prefer to use an alternative to protect your computer, you may want to disable Windows Defender. Below we will see how you can permanently disable Windows Defender.
Open the Notepad (or text editor), copy and paste the following text:
Windows Registry Editor Version 5.00 [HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender] "DisableAntiSpyware"=dword:00000001 [HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender\Real-Time Protection] "DisableBehaviorMonitoring"=dword:00000001 "DisableOnAccessProtection"=dword:00000001 "DisableScanOnRealtimeEnable"=dword:00000001
In Notepad, press Ctrl + S or from the File menu, click Save. The Save dialog box will open. There, copy-paste the following name along with the quotes: "defender.reg". Quotes will ensure that your file has the extension ".reg" and will not be saved as .reg.txt.
Save the file anywhere you want.
Right after that you can double-click the * .reg file. you created. Confirm the UAC question and click Yes to add it to the Registry. Then you will have to restart your system.
Below you will find the files for the Registry. Also included is a file that will help you restore the application if you ever need it.
The zip file contains the disable.reg file that will disable the application and the restore.reg file that will restore it if you ever need it. After each application of files your system will need to reboot.
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I do not know how effective it is (so all Antivirus is effective until you get the virus), but it does not bother me at all. He does his job quietly and does not blame you.