Im from a small mining town, the only reason the place isnt a ghost town is the local mines, witch means random drug tests every shift, i know a lot of my mates before heading back to work like to go for a bit of a jog to sweat whatever they may have in their system out, cut out arm holes from a large garbage bag and make some pants, chuck on layers of clothing and just run and sweat it all out, also works if you wanna lose weight if anyone was interested haha, i know a few boxers do this as a last ditch effort to cut weight, works for getting them naughts outta your system, though this is for those who know they will be drug tested, another trick around town is those rehydration packs, little pack of salts you mix with water to hydrate your body replaces all the hydralytes in your body, drinking a shit tone of those and pissing it out is meant to help as well, but for a proven method just buy some detox drink theres plenty out there and a few home drug test kits to test yourself before you head back to work, THC can be sweated out pretty easily but stays in your hair for months.
good luck in the future!