How do you get rid of yellow jackets?

Find the nest first. Watch at dusk which way they fly - a lot of yellow jacket nests are in the ground, under a deck or in a gap in the siding. Treat it after dark, when they're all inside and slow. An insecticide dust puffed into the entrance works better than spray, because they carry it in themselves. Don't block the hole beforehand, they'll just dig another way out, sometimes into the house. Traps only catch stragglers. If the nest is inside a wall, or anyone in the house is allergic, get a pro. Nests die off over winter and don't get reused.