You shouldn’t have to!
The Packs are designed to keep produce contained within them, even under thousands of pounds of pressure. This enables you to press juice with no mess. From time to time, juice may splatter or drip from the spout. If that happens, just wipe the Press with a sanitizer towel.
Please note: do not spray cleaning fluids directly onto the Press, especially the hinges or square holes in the juice chamber. Always use a moistened cloth to wipe surfaces clean.