Yes, burdock. Remember that any chemical that kills it will also kill or damage other plants. It's hard to limit the over spray on plants that large.
Burdock is a biennial, which means it has a two year life cycle. Last year it was there with big basal leaves and no stem. This year it produces a stem and seed, and when it does, it naturally dies. If you just cut the stems now, it might come back a third year, until it produces seed. IF you want it to die naturally, you will need to wait until the first sticker balls are ready to open with ripe seed. Then you can yank it out, and if you don't get all the root, it will continue to die.
If it were me, I would just get a shovel and dig it out. The plant has a deep tap root, and you will need to get all most of the root out, at least a foot down.
