I ran into this issue just recently when I wanted to test my app with multiple live ids. I have an Azure Mobile Service that I use the live id with. Basically I remember being asked for whether the app can use my credentials or not at least once. Now the LiveAuthClient CanLogout variable is always false so I can't log my account out in order to sign in with another account.
I found some reference saying that I would need to remove some single sign on stuff by hand, but I could only find one thing in Credential Manager that was seemingly similar and removing it (MicrosoftAccount:sth) had no effect. Here's the relevant piece of my code:
LiveAuthClient liveIdClient = new LiveAuthClient("myserviceredirecturi");
LiveLoginResult liveAuthResult = await liveIdClient.InitializeAsync(new[] { "wl.basic" });
if (liveIdClient.CanLogout)
liveIdClient.Logout(); // Code never goes here, ever.
LiveLoginResult liveLoginResult = await liveIdClient.LoginAsync(new[] { "wl.basic" });
The last line logs me in with the current windows 8 live id. How can I test with multiple live ids?