Stent with string

Hello. My brother is 24 and has only one kidney. Three months ago he had a UTI and 8mm stone in his upper ureter. He took some antibiotics and UTI went away. They put a double J stent in his ureter to prevent the blockage of the ureter by the stone.  After 3 months they removed his ureteral stone with laser,removed his doble J stent and put another stent which has a string. They told him after 15 days to go back to the clinic and have the stent with the string removed. Does the removal hurt a lot? He is so against medications and he hasen't taken any medications for pain so far besides tylenol and he is very scared of the pain. Do they remove the stent with some anesthesia? if yes, what kind of anesthesia? is it local? or epidural? or maybe without anesthesia?  Another concern is that his doctor decided the stent with string to be in place for 15 days..but we read in internet that almost nobody has his/her stent with string for that long time. We are worried is it dangerous that the stent will be in him for 15 days? We would be very thankful if somebody clarifies these things for us. Thank you so much in advance.