Time. At least that is the only thing that Dr. Drew says will work, and he is a leading addiction specialist. And he pretty much tells it like it is.
Sorry, I wish there was a better answer for you.
There might be something that will give a false positive that you can take to mask the results - a scapegoat so to speak - but I do not know any for THC.
Mostly, you have to weigh the possibility of getting caught, with the seriousness of the punishment (e.g. will you lose a job, not be hired, go to jail, die? All can happen depending on the situation and the drug.) (I know you aren't going to die from THC.)
Cranberry pills and vinegar mixed with water. Or they have some detox stuff the sell at drug stores.
Don't get caught!:)