Computer Configuration > Administrative Templates > Microsoft Edge - Default Settings (users can override)
Both
HKLM\Software\Policies\Microsoft\Edge\Recommended
For users in an Entra ID Microsoft Edge profile, this policy controls whether the Microsoft 365 Copilot Chat icon will be shown in the Microsoft Edge for Business toolbar for Microsoft 365 Copilot licensed and unlicensed users. This policy only applies when users are accessing Copilot in the sidepane. If the policy is enabled: Copilot will appear in the toolbar. If the policy is disabled: Copilot won't appear in the toolbar. If the policy isn't configured: Otherwise, Copilot shows in the toolbar and users may enable or disable Copilot from showing by using the Show Copilot toggle in settings.