You may need to keep him confined to a safe room and limit his contact with people. If your dog is possessive of food, treats or a certain place, don't allow him access to those items. In an emergency, bribe him with something better than what he has. For example, if he steals your shoe, trade him the shoe for a piece of chicken. Spay or neuter your dog.
Intact dogs are more likely to display dominance, territorial and protective aggressive behavior.
What Not To Do Punishment won't help and, in fact, will make the problem worse. If the aggression is motivated by fear, punishment will make your dog more fearful, and therefore more aggressive. Attempting to punish or dominate a dominantly aggressive dog is likely to cause him to escalate his behavior in order to retain his dominant position. This is likely to result in a bite or a severe attack. Punishing territorial, possessive or protective aggression is likely to elicit additional defensive aggression.