Hi, I Suggest not do delete Windows Defender and its now default antivirus/firewall provided by Microsoft. If you still want to delete it please do follow the below process to un-install manually.
1. Open a command Prompt and type the following to stop and then delete the Defender service:
- type in : sc stop windefend and press enter
- type in : sc delete windefend
2. Next you need to grant full permissions to and delete the following registry key so the Defender Control Panel entry can be deleted: open RUN command and type in regedit
3. Also grant full permission and delete the Defender program registry key:
- HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows Defender
4. Now take ownership of and delete the following folders:
- C:\Program Files\Windows Defender
- C:\ProgramData\Microsoft\Windows Defender
- C:\Program Files (x86)\Windows Defender (for 64-bit users only) and reboot the computer.