General rule, cakes need to be trimmed before frosting. This is especially important if you are making a layer cake of any kind. It is not your fault, when you bake a cake, it does not come out of the oven with uniform height: one part may bulge, or some other part may sink, making it even and flat is important. The sides also require some attention, the harder outer edges should be removed. Every bite of cake should be consistently soft and moist, there should not be hard pieces in your way. This is an especially important technique when making an all white cake such as in Dre’s Coconut Cake. You should not see brown edges peeking through the white frosting. Below are some relatively simple steps to follow to try to make cake layers more uniform and even.