The most effective way to turn transparent phone case yellow is to rinse with water:
1. If there is grease on the silicone sleeve, apply soapy water, wipe the stain with a soft cloth, and then rinse it with clean water. Dry the water with a napkin or a soft cloth and leave in a cool, ventilated place to dry.
2. Rub with an eraser.
3. Wash with alcohol or some toothpaste. (Use less)
4. Use sellotape or tape.
5. Here is a warm tip, silicone mobile phone cover must not be exposed to the sun, in addition, do not clean too frequently, will backfire.