The first one: gently rub with a dishwashing detergent, then rinse with water, after drying, it can be dried. Remember, don't burst!
The second type: If there are more silicone tubes, you can put them in the washing machine and wash them with bleach. However, the disinfectant should be selected with some odorless or fruity disinfectant.
Third: Wipe the silicone tube with a rubber.
Fourth: Clean the silicone tube with alcohol or by applying toothpaste.
The fifth kind: Sticking with transparent glue or tape, there is a wide-width transparent glue on the market. Use it to glue two or three times to try the effect. Maybe some small dust can be used. If the silicone tube is too dirty, it will not work.
Sixth: Apply a small amount of wind oil to the stain with a cotton swab. After 1 minute, wipe it off with a cotton swab to remove the dirt.
The seventh type: short-time steam sterilization or hot water cleaning silicone tube with temperature heating up to 150°.