To remove an email account from Microsoft Authenticator, you must first unsync it. However, if you are unable to unsync the account because the app is stuck on "Getting things ready for you," there are a few steps you can take to resolve the issue. First, try force-closing the app and reopening it. If that doesn't work, try restarting your device. If the issue persists, you can try deleting and reinstalling the app. If none of these steps work, you can contact Microsoft support for further assistance.
References: