Unfortunately, I just had to deal with that over the past month and the answer seems to be, you don't. I had two just outside my bladder with a pretty bad infection in my left kidney. They first started a round of antibiotics and inserted a stent (hospital) from my kidney to bladder so the infection could drain and clear up. Once that cleared up, they went in to blast the stones away (out-patient). Then 5 days after that, they went in again (office visit) to remove the final stent. It's amazing how bad a kidney stone can make you feel and how much better I feel now. If you have one now, good luck.
I small & floating they can pass on their own. recommend drinking large amounts of water. If becomes obstructing or over 1 cm then surgical procedure is done by Urology to crush them to smaller pieces so they will be able to come out.