If you're not planning on using Outlook I'd remove the Gmail account from Outlook to prevent it from connecting to your account again. Other than that, nothing should be required.
Also, there are settings in all e-mail clients including Outlook that allow you to keep the mail on the server so it's not moved off of the server and onto computer. This would allow you to read all mail on both your local computer and on Gmail if that is something that interests you. However, most people don't like this option because you'd have to do an action such as deleting an e-mail on Outlook and on Gmail.