the two organs you can live without are your kidney and your appendix. you have two kidneys incase there is a complication with one of them, you have a “backup.” your system wouldn’t change too much, you’d live a healthy life. you can also live without your appendix. it’s the most useless organ in the human digestive system. plant eaters rely on their appendix to help process plants , but that organ is not part of the human digestive system. again , you wouldn’t notice any major change. if you do remove a kidney however, it’s be best not to overwork it and take proper care of your body by consuming appropriate amounts of fluids. if you lose both kidneys it’s fatal.