Is it possible to cancel a bounty if I found the answer to my question?
Details on the bounty system are here: How does the bounty system work?
At the bottom of the answer you'll see that you can't cancel a bounty. I assume you're referring to this question. ændrük's answer will at least get the automatic bounty for half of the rep at the end of the period.
Personally I would just give him the full bounty for the effort (since once you spend the 50 it's gone for good). It's a good answer with nice screenshots so the next person will get a easy to use answer.