This is what I managed to do with an old toothbrush, dish soap and water. All these youtube videos suggest using bike specific degreaser, is just soap and water good enough? More
DIY Homemade Bicycle Chain Degreaser Cleaner: How do they compare to the real thing - YouTube
Keep things clean with Finish Line's range of degreasers
How to Clean and Lube Your Bike Chain | Reviews by Wirecutter