Cleaning an iPhone silicone case? Start with a slightly damp lint-free cloth
Apple recommends removing silicone or clear iPhone cases and wiping inside and out with a slightly damp, soft lint-free cloth. Avoid household cleaners, abrasive agents and peroxide.
Cleaning a case while it remains on the phone risks moisture reaching the device. Apple's official instructions for silicone, clear, polycarbonate and TPU cases favor a slightly damp cloth over harsh cleaning chemicals. Leather, FineWoven and TechWoven have different instructions.