Wasps are much more aggressive than bees, particularly if their nest is threatened, and multiple stings may result if you do not wear suitable protective clothing. You can treat the nest yourself ( see below) but you should consider these risks carefully before attempting to do so. (If in doubt seek professional help.)
Dealing with the problem yourself
If you do decide to treat the nest yourself, suitable products can be purchased from hardware shops and garden centres. You must first locate the entrance to the nest. Following the flight pattern of returning wasps may help. Treatment should be carried out very early or late in the day when activity is at a minimum (the evening is preferable).
Apply the insecticide to the entrance of the nest, or directly on to the nest if it is visible. Do not hang around to admire your handiwork, wasps get angry when disturbed. Keep well away from the treated nest for at least 24 hours.