OK So we deal with drug testing a lot in the athletic world and I went and pulled out the textbook for you... So, it says: "Marijuana also contains unique substances (cannabinoids) that are stored, much in the same manner as are fat cells, throughout the body and in the brain tissues for weeks and even months. These stored quantities result in a cumulative deleterious effect on the habitual user. "
- Taken from: "Arnheim's Principles of Athletic Training: a competency based approach" pg. 480.
So I guess that's your answer. I do know, however, that most athletes won't test positive within a week or two, depending on the individual. If you have to take the test, all you can really do is hope for the best. I apologize, but I am unfamiliar with products that may help eliminate detection.
HTH!