You can also use food to teach the drop. I do both this and the above method, at different times. If it’s a stolen object, this is usually the method I use. If it’s tug, I’m more likely to use the method above, unless the dog is very strong.

At first, you are basically bribing your dog. But you gradually transition to him expecting a treat when you ask him to give, so that the toy or human item falls out of his mouth. At that point, you can start rewarding only some of the time, more like a
slot machine than a coke machine. Let’s say he has a Kong in his mouth.

First put the food right next to his mouth and ask him to Give. When he drops the Kong, click and toss the treat, so you have time to pick up the Kong. After he knows the Leave It cue, you can use it to keep him from going after the Kong once he drops
it. If his teeth touch you at any time, the Kong should disappear and he should find himself alone in the room.

Next, hide the treat behind your back or on a shelf, ask him to Give, then present it within a second, clicking and tossing the treat when he drops the Kong. Do this a LOT, Work up to two or three seconds between the cue and the food appearing. Repeat several times, stay at this level for several sessions, consistently giving him food for dropping the Kong, until he starts dropping it after you say Give, but before you present the food. The first few times he does that, give him a Jackpot and make a big fuss.

After that, treat him for the times when he drops the toy on cue (without the “bribe”). On the other times, use the treat to open his mouth but do not give him the treat; tossing the Kong is enough.

See also: “Teaching Your Dog to Fetch“, which teaches yet another way to get dogs to drop toys, etc.