Once removed, it has to be removed permanently. DO NOT give in to a tantrum because you had a rough day or there's another reason you don't want to deal with the fit. If a child gets a highly-desired item once every 10 times (on average) he tantrums, it becomes like a slot machine, where any fit could produced his beloved Nuk, and he'll tantrum constantly. Tantrums and other problem behavior will quickly extinguish when they don't produce the Nuk. Similarly, don't attend to the tantrum or console the child when he's throwing a fit - he'll learn to put on an act when he wants attention. You absolutely need to provide other preferred items (juice, tickling, playing, praise, praise, praise) initially when the child is being good and not demanding the Nuk at times he'd usually get it, and then gradually fade out the rewards for going Nuk-less. When telling the child he can't have the Nuk, be very matter of fact, don't bargain with him, and don't give in to yelling. Simply state something about how he can't have the Nuk anymore and provide a reason he'll relate to ("big boys don't need those" or something to that effect usually works).