Does your child share his toys with his friends or siblings? If not, how do you handle it? Do you snatch it from him and give it to his brother? That is the worst thing a parent can do as it does not instill the idea of sharing but develops a kind of discontent and irritation towards the other sibling.
You should realize that instead of obeying you, your child will develop a feeling of rivalry. Some more kind kids will not have a trouble giving out their chocolates with their siblings or best friends, but most other children are far more overprotective about their possessions. This is the period when kids start valuing and developing a fondness towards certain things, and they also know that it is far too easy to have these things taken away from them.
Kids don’t part with their belongings is as they believe they don’t have power over them. The instant your child knows that his toys are owned by him, and he can get them back whenever he wants, he will be keener to part with them.
For making it easier every parent should play give and take games with their child. If your child is overprotective about a specific thing, kindly ask her if you can take it from her for a while. If she gives it to you, you can hug the toy, tell her how much you love her and love the toy and then maybe give it back to her. Don’t forget to give it back to her in a few minutes so that she feels that she has made the right decision by giving it to you and wouldn’t mind doing it again. This would probably make her realize that her toy is going nowhere and she can have it when she wants. She would feel more comfortable at sharing next time.