Or you may want to close your store to rentals after a certain time.
But you are actively renting the items right now so you don't want to set them as unavailable yet.
In both cases you will want to create a 'blocker booking'. A reservation that prevents the item(s) being booked from that date.
Simply make a reservation containing the item(s) in question, for a period of time.
You will then either sell on the items, or make them available again.