There’s a power cord plugged into a standard outlet near the softener. For total shutdown, unplug that sucker. It’s optional, though. The water flow stops at the bypass valve, so the electronics are just sleeping.
But here’s the thing: if you’re going to be gone for weeks, or you’re draining the system for winter, unplugging prevents the control board from waking up and trying to regenerate. That’s just wasted salt and water.
Heads up: Some softeners have a “regeneration cycle” that must complete before you cut power. If you yank the cord mid-cycle, you might break its brain. So wait until the display shows “Idle” or “No Flow.” Patience, grasshopper.