First of all, we should mention that along with cleaning the lighter, you should also bleed your lighter every few months as well. Bleeding the lighter is when you drain out all of the old fluid and clean the interior to get rid of any build up or air that has accumulated. This can help the lighter to ignite easier and with a better flame.
Besides this, to clean the lighter, you may want to take it to a smoke shop to make your life easier. If you are determined to do it yourself, you will need a bit of patience and to be very careful. First of all, it's best to turn the flame down a low setting just in case you press the wrong part and the flame ignites. You can begin by applying pressure to the butane valve to let out any air that has snuck in. Then you'll move on to the combustion chamber where you will need compressed air to clean out any dirt and/or build up. You may need to repeat both of these processes 2-3 times to fully clean the lighter.
Once this is finished, it would be a great time to refill your lighter and wipe down all of the surfaces. Carefully put it back together and don't forget to adjust the flame.