The question: Do you have any suggestions on how to remove goutweed?"
The answer: This loathsome plant, also known as bishop's weed, will take over every part of the garden very quickly.
Never use it except in a concrete container in dead shade. If you can, cut existing growth back to the ground, cover it with black plastic and hold it down with bricks at the edges. This will fry the plant.
Over time, keep cutting it to the ground until you starve the roots. It will be a long, long job, but persevere. The more you pull at goutweed, the more its brittle roots will form new plants. And if it goes to seed, it could infect a whole neighbourhood.