I'm never a fan of the cold turkey method on anything having to do with kids. battling with them never results in anyone winning. i wholeheartly believe that encouraging and supporting insead of forcing goes miles for self esteem and trust. there is usually something underlying (rational and not rational) that makes kids act out. it could be something a small as a loud noisy truck that flew by one day to set off a fear at this age. how you handle it can set the stage for how your son will communicate his fears with you and how he will handle them. Or maybe it is just a control thing and he is looking to see how you react.
you can start by talking to your son. Not sure how well he communciates at this age but you be surprised how well they can communicate with their body language when they don't have the verbal words. talk about places you have gone recently and things you have seen to see if you can pinpoint the issue. in simple, short sentences you can tell him about things you did/didn't like and how you handled them.
until then you can start small with fun things like for example coloring on the driveway with sidewalk chalk. tell him that you are going to color in the drive way with your new chalk and you would like him to help you color becuase it is much more fun to color with him around than by yourself. if you ask his permission he is going to say no (that's what two year olds do!. tell him what you are doing and that you will be coming back inside to eat lunch when you are done. and stick to your word. start small and build from there. if you get to venture further be really clear on where you are going, what you are going to do when you get there and when you are coming back. listen to what he has to say/watch his body language.
if it is a control issue - give him something that he can control - pick a toy to take, pick out what to wear, or snacks to bring, etc. i have a two year old and i found giving her little areas of control with in her world has been a huge tantrum diffuser as well as helped us set up boundaries.
some days we get so wrapped up in things that we have to remind eachother to take a step back and take another look at things. your mommy gut is telling you to do this. Good luck and hang in there.