Once booking is marked as NoShow, the availability is restored and the booking is no more shown on BedView.
Also, you can make the system mark bookings as NoShows automatically. See Property Settings / Preferences.
In this case, the system will mark all not checked-in bookings as NoShow at the date change.
If you synchronize with Booking.com, then just mark bookings as NoShows in FrontDesk Master and the system will mark this booking as NoShow directly in your Extranet. So you don't have to do it manually in Extranet.
However, if you mark as NoShow directly in Extranet, then the booking will be marked as cancelled in FrontDesk Master automatically.