In early spring when a wasp nest is still small, it is usually possible to knock it down with a long stick or shovel without procuring any stings. However as time goes by and the wasps begin to build their nests larger as the number of wasps increases, this is not advisable.
When the nest is small, a pest control such as an insecticidal powder in a puffer pack can be used to dust the nest and makes an effective wasp removal treatment. Various chemicals can be used, with some people even recommending gasoline as a means to get rid of wasps. Regardless of methods of pest control, this is only safe if the nest is small. As the nest becomes bigger, the traffic of wasps to and from the nest increases. A passing wasp could sting you, and if you were to kill it by crushing it, a pheromone would be released signalling the rest of the inhabitants of the wasp nest to attack. Using a wasp removal treatment yourself on a fully developed nest can result in a multitude of stings and the problem still not being taken care of.
To effectively treat a large mature nest, it is highly advisable to go with a professional exterminator, as treating such a large nest takes some experience. This is especially true if the nest is situated in a hard to reach place like a roof void or inside of a structure. Pest controllers are equipped with a wide variety of tools and insecticides to get the job done quickly and efficiently, and despite costing money, will keep you from getting stung. Most pest controllers employ lances of up to 14 ft in length to spray the nest with insecticide from a distance. Most of these lances fire a powdered poison on the wasps using compressed carbon dioxide. These sorts of insecticides are mostly carbonates, which function as a nerve toxin, are quite residual, and not available to the public. Some exterminators use a rapid knockdown liquid insecticide that, while relatively expensive, is highly effective and also not available to the public in this form.
In short, the best way to get rid of problem wasps is to seek the knowledge and resources of a professional pest controller. A professional will be able to make quick work of the problem wasps and you won’t be in danger of being stung.