Hello David, this is Emily.
In Settings> Personalization > Taskbar, you can turn off Copilot. However, if that's not enough and you wan to disable it completely, you will need to do this in registry.
To do so, launch Registry Editor, then go to
HKCU\Software\Policies\Microsoft\Windows
On the left, right click on the Windows folder, go to New > Key, name it "WindowsCopilot"
Then select WindowsCopilot, on the right, right click and create a DWORD value, name it "TurnOffWindowsCopilot" and set its value at 1.
Restart the computer to have the change take effect.