How do you get an adult male cat to go to the bathroom outside if you don't want a litter box in the house?

I assume you're talking about normal urinating and defecating, and not referring to spraying, where a male will urinate to mark his territory.

Cats actually prefer the outdoors, so it doesn't take much to encourage them. If he's clueless, take a little bit of the used litter and put it outside in a soft, earthy area you would like him to use. Take him out there, and let him smell the scent. Make sure that he has regular access to the outdoors, to play as well as to go to the bathroom.

If he doesn't immediately begin using the outdoors, begin moving the litterbox about a foot at a time (one foot per day) towards the outdoors. Yes, this means for a period of time you will have a litterbox in the middle of a room you REALLY don't want it in, but this is a temporary move. When you finally have it outside, simply empty the box and stop maintaining it. He will already associate going to the bathroom with going outdoors by then, and will improvise.

If it's spraying you're talking about - since you specifically mention adult male - then you'll need to make sure he is neutered, and then use a pet enzyme spray to eliminate his markings. If it's only a few spots, then put his food in those places. Cats do not like food & bathroom in the same location, so he won't remark those areas, while you're working on the above.

I PUT MY ONE YEAR OLD MALE CAT, HIS SISTER (ALSO HIS KITTENS MOMMA) AND THREE KITTENS OUTSIDE FOR THE SUMMER. I PUT THEIR FOOD AND WATER ON THE DECK WITH AN
OVERHANG. TWO OF THE KITTENS WERE ADOPTED AND THE FEMALE CAT AND ONE KITTEN WERE TAKEN BY MY EX-GIRLFRIEND. THE MALE CAT, CHASE MANHATTAN, STILL RESIDES WITH ME AND STAYS INSIDE PART-TIME AND OUTSIDE PART-TIME. THE GOOD NEWS IS HE STILL USES THE GREAT OUTDOORS FOR POTTY-TIME ! WHAT A RELIEF ! NO PAYING FOR LITTER OR CHANGING THE LITTER BOX AND THE HOUSE SMELLS TERRIFIC !!!! HOPE THIS HELPS. SINCERELY, B-MAC

First: Eather have him on a leash or if he is an outdoor cat let him out and go out with him.

Second: Were ever you want him to go every time put the litter box there.

Third: Put him in the litter box and tell him to go potty or go to the batheroom what ever he's use to. {repet for a while}

Forth: After you have repeted step 3 for a while take him out with out the litter box in "The Spot" and tell him to go {Give him lots of luv too}

Fifth: After a while your cat will be going potty out side :D No more litter boxes!!!!