Once the M$ Office plugin has been installed it demands a user name and password relentlessly: a user who has either forgotten her password or does not want to login to Alfresco has no way at all to escape the Login Window! More to the point, a developer who wishes to change his URLs is forced to login first to the repository he does not want to see.
Selecting 'Cancel' simply leads to the Login window being redrawn.
Entering wrong data appears to offer the choice of 'Retry' or 'Cancel' but both options identically return to the Login box.
The only way out is to kill WINWORD.EXE from the task manager.
The only way back into Office would appear to be to uninstall the plugin.