The Copilot app is not even an app, it's just a shortcut to copilot.microsoft.com webpage. Uninstalling it doesn't actually uninstall anything from the computer, it just removes the shortcut to that website.
- In Word, Click on the File menu and select Options.
- Cick the Copilot tab in the Word Options window, then uncheck the Enable Copilot checkbox.
- Click OK to save the changes and restart Word if necessary.
This page has more detail, but the steps above are really the meat of it. https://support.microsoft.com/en-us/office/turn-off-copilot-in-microsoft-365-apps-bc7e530b-152d-4123-8e78-edc06f8b85f1