I have a cactus that fell off a car. Long story short, people getting in car, placed cactus on hood, forgot cactus on hood... The top third of the cactus is damaged and the pot was destroyed. I replanted in a new container. Can I just prune the top off?
Prune off the damaged portion, but only if you can differentiate the section that was broken and not cut into the parent basal section. You can wait until the damaged section dries up and reveals the dead from the living tissue, then prune off the dead portion only. Or leave it as is and the dead tissue will eventually fall off, or re-grow and cover the damaged area.
Does that plastic TupperWare type container have drainage holes? If not, better to drill holes in the bottom or get a new proper container, and use a catus/succulent potting soil that can drain well and not stay wet.