Honestly, that depends on how much YOU are willing to spend on it, and how close to original you want to keep it, with wiring, etc.
The EASIEST answer is, remove the front driveshaft. Viola! It will be 2wd at that point. But I presume that's not the answer you were looking for, right?
Beyond that point, when it comes to pulling the transmission and transfer case out and replacing them with a 2wd transmission, replacing the front suspension with a 2wd set-up, replacing all the wiring harnesses to work with all those changes, etc. the honest answer is most likely going to be- sell your 4wd to someone that wants a 4wd, and use the money to buy a 2wd version. Anything else is going to wind up costing you MORE money than doing that, by the time you are finished.
Now, I don't have anyway of knowing if you have some personal attachment to the vehicle (first car, etc.) so that might come into it. I get that. But if you are just trying to do this because the 4wd part is broken with the idea of saving money by just making it a 2wd, I think that's going to disappoint you in the long run with the end result.
I'm not trying to be a jerk about; just trying to offer you some honest advice. But in the end, it IS your truck and your wallet. So IF you're dead set on doing it, I'd say at the VERY least, buy a complete working 2wd version of the same year/engine/transmission type, and look at swapping all the parts across from one to the other. Then, once you have your truck finished, sell the remains of the parts truck and your 4wd parts to help recoup some of the money you spent on the 2wd truck in the first place. Good luck either way.