I know people who have used shampoos that are meant for this and failed miserably. If you have the chance then quit.
Now if you get smart and shave your head you had better keep going! They will search your body for a hair and find one unless you are a VERY aggressive shaver
So if you have awhile before the test, first quit using. Then shave ENTIRE body(Yes ass hairs too, lol), Let hair grow back to a couple centimeters. Should be clean.
Hair testing for jobs they usually go back three months. I am not sure how long of a sample is needed for this. So they may actually say you were trying to falsify you test results if you go in shaved or with little hair.
Still none the less I would try my method vs. a Macujo method that may or may not work. This is your life we are talking about really so do your best to get this right.