Is green tea a good detox for marijuana?

Yes. Any liquid substance does. You get high from the abundance of THC in your bloodstream. Eventually the THC will make it's way into your urine as it is deemed waste by your body. Basically, the more liquids you drink, the faster it's out of your system. This is true of only those systems that are regularly filtered by the kidneys or liver, the garbage-men of the body. Consider though that THC can remain detectable in hair samples for up to six months, and even if most THC is washed from your urinary output, enough can remain to make results suspect and motivate a tester to require a more expensive hair test.