You will need a terry washcloth, a bar of soap (this doesn’t work with liquid soap), and about ½ cup to 1 cup of baking soda. Wet the washcloth and suds up the bar of soap to create a nice lather. Then sprinkle about a tablespoon or so of baking soda onto the washcloth, work it into the terry a bit, then start scrubbing your body with this mixture. Pay special attention to the back of the neck, the underarms and wings of the lats, crosscuts on the abs, elbows, gluteal folds, fronts and backs of knees, ankles and feet. You will definitely need to repeat this sudsing technique on the washcloth, adding more soap and baking soda each time.
With this method I usually manage to remove a good 80% or more of the product with one washing. This method also serves as a decent prep for the next spray tan since it is an effective exfoliator.