If you type
credential into the Start Menu search box, you should get Credential Manager which is what the "Manage network password" dialog now gives. That should show any credentials that have been saved. Another method of browsing these credentials is the Nirsoft Network Password Recovery tool
As far as I can tell, if your normal Windows username/password is the same as the remote one, it's not saved anywhere and you can't make it "forget" (it uses it automatically and only prompts if that one isn't valid). Others should be visible, although after deleting them you may need to reboot - I found that my shares remained connected and drives remained mapped until I rebooted.