There doesn’t seem to be any full-proof way of doing this in 24 hours. From what I’ve read there are a couple of things people try.
Baking soda
This sounds like a horrible thing to do. You have to dissolve a tablespoon of the stuff in water and drink it down (maybe have something to eat with it?) It makes you very nauseous but you have to keep it down. You do this once per hour for three hours. A bad side effect is the diahorrea. People who swear by this method say after about the 3rd time you urinate it will be clear. Test yourself with a home testing kit.
There is a good answer on Blurtit here //drug-alcohol-testing.blurtit.com/1664353/will-baking-soda-make-me-pass-a-urine-test-for-meth
It sounds like it could work. But on the negative side I’ve read an article from a woman who works in a drug testing lab and she is convinced that it’s not that simple!
Her main points are that drug testing methods are getting more and more sophisticated and they are hard to cheat.
It’s not only unpleasant but very bad (sometimes dangerous) for your health
Cranberry juice
Reading the forums it would appear that there may be some truth that drinking cranberry juice helps. The following is taken from a urine drug test information sheet - Methamphetamine and Amphetamine link here
Detection in Urine: When methamphetamine is used it is metabolized to amphetamine and both are eliminated in the urine. Typically, the detection time following the last dose is 1-5 days. The longer detection time is for high doses and high urine pH (low urine pH results in a shorter detection time and can be caused by drinking cranberry juice)
However there are many who say it’s just not true. It’s certainly not worth relying on it in my opinion.