the only sure fire way is to pull it out [relatively easy] before it seeds. if there are no flowers in evidence you can hoe them over and allow them to dry/die on the surface. But once there are seed heads they can produce from 100-300 seeds per plant. the seeds will lie dormant until disturbed by us digging. so vigilance is the key word.

Just keep pulling it out - at least it comes away easily.

I use a garden fork to ease the plants out preferably before they seed. I was blaming my influx of sparrows for the chickweed but now I am beginning to think it has arrived in the compost as it seems to be a growing problem for gardeners all over the place.

I miss small plants and then when i do find them they have already seeded hence the continued appearance of the little blighters.