The Windows Defender Security Center icon sits on the right side of your Windows 10 v1703 taskbar, ready to warn you if your PC requires your attention. When all is good, it will display the green check mark on the white shield icon. If something requires your attention, it will display a red cross sign.
Windows Defender Security Center act as a dashboard for all of your security features, including third-party security to give a clearer view of any risks your PC may face. It’s been specially designed to simplify and unify all the various security settings of Windows in the same place
Disable Windows Defender Security Center taskbar icon
If you do not like looking at the icon for some reason, you could simply drag and drop it in the Hidden icons bin.
But if you want to disable the icon from starting up and displaying in the taskbar, you will have to disable it from the startups.
To do so, right-click on the taskbar and click on Task Manager. Now click on the Startup tab.
Look for the Windows Defender notification entry. Right-click on it and select Disable.
Restart your computer and you will not see the icon.
You can also use any third-party Startup Manager software to disable this icon or manage your startup programs.