to weed, to eradicate
薅 centers on removing unwanted growth: weeding out plants or eradicating something undesirable.
薅 is a phono-semantic compound with 艹 (grass) and a phonetic element related to 好 or 休, but the exact historical development is uncertain. The character is rare and its origin is not well documented.
The grass top 艹 sits above a shape that looks like a person 女 working with a tool 寸 among plants 辰. Picture someone pulling weeds out of a field.
For コウ, imagine a gardener saying 'Cut out!' as they weed: 'Cut out' -> コウ, and the weeds are eradicated.