Here is an outline of how to make stored cannabinoids avaliable for metabolization.
Summed up.
Maintain a moderate strength training regime and zone 2 cardio regime as part of your weekly routine.
Prepare for fasting with a couple of days on the ketogenic diet. Maintain training and zone 2 cardio.
Fast for 72 hours. Himalaya salt or generic electrolyte supplementation to combat lethargy and brain fog.
Break fast with ketogenic foods. In the next few days, increase calories slowly in a range similar to 800-1200-1700-2200 kcal. Start up strength and cardio at the 1700 kcal mark.
Urine tests (in various sensitivities before, during and) after the elimination period for control.
Moderate strength straining and zone 2 cardio
The reason for strength training is to build muscle. By carrying more muscle your general energy expenditure will go up, which means that you will burn more fat when fasting.
The reason for zone 2 cardio is training the body's capacity to burn fat. In technical terms: Increased mitochondrial function.
A weekly routine that incorporates this will build a body that might be more adept at eliminating THC from the system.
Try to loose a little weight over time, as less fat stores means less places to store THC. And yes, the legal THC-limits might be a bit discriminatory against overweight individuals.
Optional idea: You might want to do get into a intermittent fasting routine to build some limited fasting experience and build some endurance in caloric restriction. If you want to proceed with some precaution, you can check out Dr Eric Berg's conservative approach to introduce the body to intermittent fasting.
Keto before fasting
The idea is to adapt the body to utilize fat as it's primary energy source before you deprive the body of foods with a 72 hour water fast. It is not mandatory, but it is a good idea to deal with brain fog from adapting the brain to ketones separately from pangs of hunger. Keep training during keto. Perhaps avoid strength training the day before you initiate the 72 hour water fast.
Maintain a water fast for 72 hours
Drink water. Once in a while you can add Himalaya salt or commercial electrolyte supplements (if it has a negligible amount of carbs it is okay) to keep lethargy and brain fog at bay. Do not do strenuous exercise, but keep moderately active by doing chores at home or taking a walk in the park. 72 h fasting can be a bit rough. Do not overexert yourself, but stay in motion within reasonable limits. Don't eat, but stay hydrated.

Here comes the most interesting part (1).
If we look at the THC column for subject A, a 54% decline in THC is observed. In many subjects there is no THC detected, most likely due to degradation of THC in blood samples during storage.
Moving on to the Serum THCCOOH column, the values after food deprivation (FD) are higher than those before FD. We can assume that the elevated levels of THCCOOH in blood is a result of metabolized THC released from mobilized body fat.
In the Urine column we can see that the values are much lower after 24 h fast.
Break the fast gradually with ketogenic foods
Some suggest that ending the fast with a slow introduction foods, starting with fat and proteins. Continue with gradually increasing caloric intake over a few days. Breaking the fast onto a ketogenic diet for a few more days will maintain a high fat burn which is quite helpful in relation to the clearance of THC.
Strategic use of urine tests to verify elimination
During the fasting period, urine test of high sensitivity can be useful. If you test positive on a higher sensitivity, you have documented increased levels of THCCOOH, which is a result of the metabolization of THC.

If we look at the graph for subject A, the hard line is THCCOOH in urine. Between 96 & 120 hr is the fasting period. Take note of the tremendous peak after the low point at 120 hours. The urine sample was probably watered by excessive drinking to supress hunger, and when food is reintroduced a novel peak(relative to 96 hours ) is observed which is most likely more representative of clearing of the buildup of THCCOOH in blood during the fast.
Between 96 & 120 hr we can see an increase of THCCOOH in serum and a drop of THC in serum. Indicating the relationship between metabolization of THC and THCCOOH.
Sources
Illustrations from: