You can delete an account in outlook and it won't have any effect on the webmail itself. See if this gets you there-------------
I believe it is synching with an Xfinity mail account. When I am in Outlook and go to File, Accounts, there is only one account showing using my email address. However on my left file folder pane in Outlook there are two accounts listed. Unfortunately, this newer version of Office and Outlook was installed by a so-called professional, who, apparently did not know what he was doing. I wish I could post a screen shot. My folders pane shows two account with exactly the same name - my email address. I believe one of the accounts is leftover from my Outlook 2010 and I have deleted many folders from it. I only use one of them. But, as I said, in File/Accounts, only one account is listed.
I guess I'll just have to deal with it. I appreciate your efforts, but unless I could show you what my screens look like, there's no sense in spending more time on it.