Ok what you need is consistency.
I deal with teenagers with behavioural problems and half the time their problem is a lack of discipline and consistency at home.
Never ever threaten to do something that you cannot do. Like the banning pressies, he knows this is an empty threat, you know it is an empty thread, so he disregards what you say.
Think of some doable punishments and let him know what they will be. For instance, he has to sit on the bottom stair for 4 mins until he says sorry. Or he gets a favourite toy taken away for a day.
Don't change your mind. Once you've settled on a punishment you have to go through with it, you can't go back on it just because he gives you a hug. He needs to learn that actions have consequences.
Punish the deed straight away, not later on or tomorrow. One punishment for one wrongdoing, don't say things like "because you were naughty yesterday you can't have xxx today".
You fear your son, a 4yo, and he knows this. Atm he rules the roost. You have to take back control. Be firm but fair. Never do anything in anger. Explain to him why you are punishing him.
Remember to reward any good behaviour. Tell him what a good boy he is, even if he's just sat and played on his own for 5 mins.
Do a star chart and at the end of the week, if he gets an achieveable number of stars, you both do an activity together, like baking biscuits or going to the park. Kids like that get an awful lot from personal contact, if you just get him a new toy and expect him to play with it by himself that will not work.
He craves attention. Atm he is getting more attention from being bad, than he is from being good. So don't go on and on about his misdeeds, punish him and then forget all about it, don't ever bring up past things he has done. Give yourself a target of praising him at least 5 times a day and making some time to do something with him, just you and him.
You need to work on your relationship with him. This little lad desperately wants some kind of relationship with you and this is the only one he has so far. Don't let him grow into one of the teens I have at school. You can turn this around.