You mean "lock-out" so they can't be used?
Many brake calipers have a release lever on them. Close the release lever, and you get positive braking. Open it, and you either get zero braking, or very minimal braking.
Center pull and canti brakes have a straddle wire. Remove that, and you get zero braking. Likewise, you can remove the noodle of a V-Brake.
You could also simply remove the brake pads.
Keep in mind that a brake system with slotted fittings requires some tension, otherwise it can all fall apart.