Marking it's territory. Wants your female even though your cat has been spayed. Doesn't make any difference to the male even if male it neutered. They still get the urge.

If you don't want you cat attacked then I suggest you keep your kitty indoors period. There really is no reason to put you female outdoors. They are just as happy as indoor cats.

Why put you female through the motions of mating when it can be avoided all together. It really isn't a pleasant thing for any female.

Keep chasing the male away from the house and he may eventually give up the whole thing and go else where.

One cat is telling other cats to stay way.

Because, as you have a female, his natural instints tell him to mark the territory so that other males will know that "portion of land" and that female are already occupied.

I agree with all the answers. The male cat is 'spraying' ,not peeing. Clean the area thoughally, with something like 'dettol', it,ll detere the male[s]