Navigate to User Configuration > Administrative Templates > Windows Components > Windows Copilot. On the right-side pane, double-click on the policy Turn off Windows Copilot and select Enabled. Click ...
Navigate to the "Sidebar" section within the settings. Under "App Specific Settings," select "Copilot" or "Bing Chat" depending on the labeling in your version. Toggle off the "Show Copilot" or "Show ...