In my preschool class I see these behaviors all the time (as well as with my own daughter)! At this age they are just learning how to deal with their feelings when they are angry/frustrated. It is important to acknowledge the feeling ("Boy, it looks like that made you really mad when they took that toy from you/knocked over your block tower/etc.") and redirect the behavior into a more appropriate response ("You may not hit but you could ask for the toy back/tell them you did not like it when they knocked down the tower/etc.) At first children often need to be prompted through each step and even given the exact words to say.....and it takes many repetitions of this help over time in many situations for children to begin to respond appropriately on their own. The appropriate response varies depending on the situation and the child. Some children need the strategy of removing themself from the situation until they can calm. You need to adjust for what you know about your son. If he is very active/physical he may need an appropriate physical activity to work off steam when he is mad (pound some playdough, bounce a ball, etc). The use of the phrases, "I hate you!" or "I don't like you any more." are also common. I am always careful not to become upset or hurt by this and to calmly say, "I still like/love you." and then move into the labeling of the feeling and following steps described earlier. Later, when the situation is over, you could have a discussion about how saying those things hurt your feelings....but in the heat of the moment is it best not to give those words any power by a strong reaction. Kids need to know that everyone gets angry/frustrated/sad sometimes and that those feelings are okay. They just need to learn appropriate ways of expressing and handling those feelings and situations. I hope this was helpful.