The easiest, quickest way to be rid of dandelions is to form an intent to eat them. Their leaves make an excellent bitter green either to include in a salad or serve wilted as a side dish. (My personal favorite way is with Pennsylvania Dutch-style hot bacon dressing. YMMV.)

In any event, shortly after the minute you decide you're going to eat them, they'll disappear. If they're slow, go out and cut a couple and the others will get the message.

Works every time.

fiery, dependable, occasionally transcendent