Removing the smell of dog urine involves either using a high-quality pet odor neutralizer or a natural cleaning agent. Hydrogen peroxide, undiluted white vinegar and baking soda are natural agents that can help remove the odor.
According to the Humane Society, pet owners first need to thoroughly clean the affected area. Urine should be soaked up as quickly as possible; once it dries, the odor is harder to remove. If possible, the area should also be rinsed with fresh water. A wet vac works well for this. To completely remove lingering odor, a high-quality pet odor neutralizer from a pet supply store should be applied to the area.
HealthyPets.com has several suggestions for using natural cleaning agents. One is combining one part hydrogen peroxide with two parts water, and allowing the mixture to soak in for up to 10 minutes before blotting. Undiluted white vinegar can be used as an alternative. Pet owners can also cover the area with baking soda, allowing it to sit for several hours before vacuuming it away. If the urine has dried, the cleaning agents may need to be reapplied several times.
The Humane Society recommends retraining the dog to eliminate waste in desired areas by making the "accident zone" unattractive and the target area attractive. If the problem continues, though, the dog may have a medical condition that requires a trip to the veterinarian.