How do you get rid of weeds Animal Crossing?

You can get rid of weeds by either pressing B while facing a weed, or by digging one up with a shovel.

However, there is one more way. In the middle of the night, on a random day, Whisp the Ghost will appear. Listen to his voice, and if you get close enough, he will reveal himself to you. If you do what he says, you can choose from a list of options he gives you. One of those options is to rid your town of all weeds.