one. If it is silica gel dirt, you can wash it with methylene.
two. If it's silicone there's dirt on the phone. Then 1. You can rinse with water: the silicone sleeve with grease should be coated with soapy water, wipe the stain with a soft cloth, and then rinse with water. Dry the water with a napkin or a soft cloth and leave in a cool, ventilated place to dry. Attention:
1. Avoid the sun.
2. Don't wash too often.
2. Rub with an eraser.
3. Wash with alcohol or some toothpaste. (Use less)
4. Use sellotape or tape.