The homeowner is responsible for removing all noxious weeds from the property. Your state Agricultural Extension Agency can fine people in some cases, when they are not removed. If you have found some coming up in your yard, here is a simple way to remove them.
Wear gloves. Use scissors to snip the flowers, and drop them into a bag or collection container. Its the flowers that usually cause the problems so dont let them blow around. Once the flowers are safely out of the way, you can pull the plants-roots and all. Again, put them directly into your bag. Tie the whole thing shut and put them into your dumpster. Dont burn ragweed.
I have to pull a little up every year at this time. It just blows in from everywhere.