How Long Does Marijuana Stay In Our System?

My weight is 114kg height 5ft6 i smoked pot for approx 10yrs i have stopped approx 8 days ago i took a home thc test kit which i failed i have started exercising .i smoked about 1 joint a day how can i get thc out and how long will it stay in my system have researched on internet there s alot of different answers out there i have to pass a drug test for work in 2 weeks please help