After de-pulping and separating, wash the beans and soak it in water overnight. There are different ways how to ferment these coffee beans considering the climate, temperature, time, and your preference of course. I really don’t know about a thing but according to some websites, soaking it in water causes some chemical reactions like enzymes to be naturally produced. This results to the breaking down of that sticky thing around the bean.
In another batch of coffee beans that I have previously processed, I did not soak it in water. Instead, after the skin and pulp are removed, I immediately spread it in a tray to dry leaving the mucilages around the bean. The coffee beans then stayed sticky and slimy. Some researchers say that the more mucilages remain on the beans, the sweeter and fruitier the coffee will be.