Although most wasps just want to be left alone, and actually qualify as beneficial insects in many situations, their large, intimidating size makes them unpopular in home gardens. Wasps may be solitary or communal, but always serve a nest. The only guaranteed way to get rid of that nest and the wasp population is to kill the queen.
Identify the wasps you see so you know where to look for the nest, and thereby the queen. Common wasps are yellow jackets, paper wasps, cicada-killer wasps, hornets and mud daubers.
Find the wasp nest. Cicada-killer wasps build their nests in the ground, in communal mounds. Yellow jackets, wasps, hornets and mud daubers build their nests on walls, in the eaves of buildings, in hollow trees, and the like. The nest will look like a ball of mud attached to its foundation, with several open cells.
Attack the nest at night when all wasps are likely to be at home, including the queen. Use a wasp-specific pesticide like PT Wasp and Hornet Killer. Spray it directly into the nest until the nest is thoroughly saturated.
Later, destroy the wasp with a broom, shovel or your foot to discourage rehabitation.
Wasps are sluggish at night and in cold weather. Some wasps lack stingers, but all wasps will attempt to attack you if you're attacking their nest or queen.