There are really only 2 things you can do. Exercise and eat a high fiber diet.
THC resides in the fat cells and thc is not water soluble so the only way to get rid of it is to burn the old fat cells and replace them with new clean fat cells. The high fiber diet helps because 75% of your thc metabolites are excreted through your bowel movements. The problem is while they're in your intestines the thc metabolites can be reabsorbed. So the idea is to keep things moving so less of it can be reabsorbed.