well if you plane on doing nothing to halp the speed of it going away, it can stay in your body for a good 3 months if your over the weight of 120+

but if you wanna pass it ASAP do this
Go to a gym work out (Sweat alot basically)
Drink tons of water (Help flush out you system)
Eat lots of Meat (I heard pork is the best for this methd (Not sure though))

do this for a good 2 or more weeks and you should be AOKAY (or just keep buying a few drug test and test your self every now and then)