Does anyone know Roblox's password apart from the staff?

No, only Roblox employees know ROBLOX's passWord. Since Roblox is an administrator, giving out his passWord to users would cause major problems. Because of this, it is likely that the Roblox staff members change Roblox's passWord every so often for security purposes, so even if someone did know his passWord it wouldn't work for very long.

Also, if ROBLOX did give out their passWord, noobs would take over, change the passWord, and Roblox Admins wouldn't be able to access it.