“How can I cleanse my gallbladder naturally?”

There is no way to do that. A gallbladder does not need to be cleansed. If there are gallstones, then you can't do much to get rid of them besides eating a low fat diet and losing weight.

Although not proven by any studies, there are formulas that may assist you that are natural. These methods involve drinking fairly large amounts of lemon juice and olive oil over a short period of time. The effect is to use the high oil content to make the GB contract forcefully, thereby expelling stones and sludge. The risk is that if the stones or sludge get stuck you could actually precipitate a GB attack. You will need to check on the internet for the different formulas.