Hello, microfiber cloth is really very important and useful in cleaning eyeglasses. And in fact, it's also very easy to clean microfiber cloth itself, you just need to pay attention to some details.
First, you should wash the cloth in warm water, and just use one or two drops of mild liquid dish soap or liquid laundry detergent is enough, make sure not use more. And pay attention to that do not use bleach to clean the cloth, since it will corrode the fibers.
Second, rinse the cloth and remove all the soap from it, never make any left on the cloth.
You probably don't want to wash the cloth by hand, using washing machine is still okay, but make sure you use gentle cycle.
Finally, put the cloth in the dryer, and make sure you use low setting. Or you can use air dry. That's it for how you can get the cloth clean.