I\'m using TFS Preview (Team Foundation Service) with one of my projects with Visual Studio 2012. I\'m also using an on-premises TFS server with most of my projects. When I
Check the information in registry : HKEY_CURRENT_USER\SOFTWARE\Microsoft\VSCommon\Keychain\Accounts and delete the related keys under Accounts section.
Clear the cache in these paths:
%localappdata%\Microsoft\TeamTest
%localappdata%\Microsoft\Team Foundation
%localappdata%\Microsoft\VisualStudio
%appdata%\Roaming\Microsoft\VisualStudio
Hope this will work.
Note: By doing this may clear all the cookies and caches and load the Visual Studio New.