I tried to open my Credential Manager, but could not find any credentials that have anything to do with my TFS account.
So what I did, instead, I log out of my hotmail account in Internet Explorer and then delete all my cookies and stored passwords in Internet Explorer, as described in this blog: Changing TFS Credentials in Visual Studio 2012

After clearing the cookies and password, restart IE and then go to your hotmail (or active Windows account).
Then start Visual Studio and try to connect to TFS, now you will be prompted for credentials.
Note: The reader said that you do not need to clear all IE cookies, only these 3 cookies , but I have not tested this.
cookie:@login.live.com/ cookie:@visualstudio.com/ cookie:@tfs.app.visualstudio.com/
Rosdi Kasim Jun 21 '13 at 19:29 2013-06-21 19:29
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