Hi there, welcome!
The peeing could definitely be territorial, and neutering should help! And you are right that the smell can cause them to remark.
White vinegar will neutralize the smell. I like to have a spray bottle of dilute vinegar (about 10%). Spray the area, blot with a paper towel. Then spray again and let it sit for a few minutes, and blot again.
For more intense stains, I have a little spot cleaner carpet shampooer, and I use Nature’s miracle enzyme carpet shampoo, it works really well.
Last thing, have you observed him peeing in that spot? it sounds like it’s right next to his litter box? Sometimes if a bun’s box is small, they will stick their bum over the side when they are using it, and inadvertently pee outside the box, even though they are sitting inside it! So a larger box can help.
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The answers provided in this discussion are for general guideline purposes only. The information is not intended to diagnose or treat your pet. Seek the advice of your veterinarian or a qualified behaviorist.