Never cut an entire food group from your diet.
i love oats with almond milk and fruit as a breakfast or a pre workout meal or oatcakes but with nut butter on as a snack! I also include oats in my protein flapjacks and smoothies.
Good carbs give you energy for the day, it fuels your body. If you only do cardio then yes do it on an empty stomach and have oats after to replenish your energy stores if your lifting weights then you’ll meed to eat before hand and oats make a great meal!