You should clean your oily skin twice a day, once in the morning and the other just before going to bed. Use warm water with a suitable, natural gentle face wash (cleansing oil, gel, foam, moisturizing soap...). 

(Forget overly irritant or abrasive soap- or alcohol-based products that risk causing a rebound effect: the skin defends itself, becomes imbalanced and produces more sebum.)

Cleansing oily skin