Easiest way to remove wasp nest?

Depends where it is and when. From about September, leave it - the colony dies with the first proper frost and they never reuse a nest. Earlier in the year, if it's small and reachable, wasp nest powder puffed into the entrance at dusk when they're all home and sluggish, from arm's length, then walk away and let them carry it in. Don't knock it down and don't seal the hole. If it's inside the wall or roof by the kitchen door, that's the one I'd pay someone for - seal that and they come out indoors.