The only proven method of ridding the body of THC is time and fat-burning exercise.

However, if youre still failing home tests and your scheduled test is 3 days away, then exercise at that point can work against you.
Whenever you burn fat cells, the stored THCA are released back into the bloodstream. From there, the THCA are filtered by the kidneys and deposited into the bladder for the eventual exit. This is the chief reason why THC carries a longer detection period than most other types of drugs.
For 3 days prior to the U/A, youd want to curtail all fat-burning activities and be as dormant as possible so you wont be releasing a bunch of THCA into the bloodstream, which will end up in the urine to be detected.