By blocking an object from being bookable through any channel, you can make sure no new reservations come in for this object. This means all availability for this particular object will be blocked.
You can use this when an object still has reservations in the future, but you don't want any new ones to be added for this object.
Open the object, and click 'Edit'. Check the box 'Blocked for new reservations'. The back-office will still be able to place reservations on this object. This will cause a notification, but the reservation can still be made.
If there are no future reservations on an object, it is also possible to remove an object setup to take it out of active rent. Read more: Remove an object from active rent.