Softside luggage can usually be cleaned with a mixture of mild soap and warm water. Dip a clean cloth into the solution and gently scrub the exterior. Then go over it with a clean, damp cloth and allow it to air-dry thoroughly. Some suitcases have removable, machine-washable linings. If not, you can wipe down the interior with the same soapy solution you used on the outside. A pre-moistened disinfectant wipe can work as well.