I only smoked one pot, how can i get it outta my system?

A few days: Since you don't have heavy exposure, if you do test positive, it won't be high for long and they might perhaps believe it's from passive smoking. Heavier use will accumulate in your body fat and it will take much longer to lose your positivity. If cannabis is still proscribed where you live / work, it's best avoided. Why use something that makes people silly?