Neutering Phoenix will not change how much he urinates. If he is marking things (seen by him peeing very tiny amounts on several objects during a walk or potty time outside), then removing the sources of the testosterone after neutering may help with this. If you feel like he is urinating more than is normal, I would discuss this with the vet and see if there is a medical cause for it, such as urinary tract infection or bladder stones, kidney disease, etc.