erase, shut (door)
銷 centers on making something disappear or become inaccessible: erasing marks or shutting a door so that what is inside is hidden from view.
銷 combines 金 (metal) with 肖, which likely contributes the sound. The original meaning relates to melting or dissolving metal, which extends to erasing or shutting.
Metal 金 on the left and 肖 on the right: imagine using a metal scraper to erase writing, or a metal bolt to shut a door tight.
For ショウ, picture a metal door shutting with a showy, dramatic clang: show -> ショウ, and the metal door is now closed.