If you have 7-14 days, go to the GNC store and they have a whole set of drinks for each day, 99.9% effective. got me through probation for the last year. Royal Flush is pretty legit too, but these are a lot more reliable
get one of the royal flush drink from any head shop and most sh*tty gas stations. Follow the directions EXACTLY. Got me through a gov't screening once or twice... You only need 48 hours clean.
What he said ^^^(you can buy in porn store or GNC too ).....and depends on your body fat and intake. If you are a smoker, 30 days is the rule for "naturally" clean......pretty much everything else only take 3 days to clean out of the body. (Which is BS, but should be discussed at another time and place.)
If you need to take the cleaner, make sure your use room temp water and avoid fatty or acidic foods/drinks for the day or days before. This also means NO alcohol. Study hard and good luck.