I believe the default password is usually Administrator
You could also try using the hot key sequence, if it has not been disabled, which is CTRL+ALT+SHIFT+SPACE
If that does not work, then it was probably given to you with an "image" applied. you would need to apply your own with a console, we use the Teradici PCoIP Management Console, there are probably others out there, with a password that you defined along with whatever other settings.
Hope that helps!