You could get that thing done at the salon where they use special chemicals/special styling tools to make your hair the straightest it can be and stay that way for the rest of your life. But it costs a lot of $ and I think you have to go through sittings throughout one whole year to get the entire process done. But since this'll be extremely damaging to your hair in the process, just try a different shampoo and conditioner- one that makes your hair straighter the more you use it. I don't know how effective these are, but this is the only method I know of that doesn't involve frying your hair by using heat tools or anything. I don't know any home remedies that changes stuff like curly hair to straight, just stuff that can make your hair smoother and stuff.
There is this shampoo that if you put it in (its natural) and straighten and blow-dry and stuff (maybe look up the details) makes your hair straight for a couple of months, depending on the curliness of your hair. You can buy it off the internet.