Open the command line by pressing Windows R, typing cmd and hitting enter. Now use the command control keymgr.dll to open a window called Stored User Names and Passwords that lists all stored usernames and passwords of the currently active profile. You can use the command Control Userpasswords2 to open the User Accounts configuration instead. If you click on Advanced in that tab you can access the same menu by clicking on the Manage Passwords button.

You may then mark any entry in the list and either remove it or display its properties for additional information. If you remove an entry you have to enter the username and password again during the next login to the service.