I own one of those microfiber bowling ball rags. You know that rag that you wipe off the extra oil off the ball? I need to know a way to clean one.
The easiest way? Throw it in a normal washer with your other laundry. Air dry to finish. Don't use any sort of fabric softener.
If you can't/don't want to put it with your normal laundry, wash it in the sink with warm water and some mild detergent. Again, air dry.
Basically, you won't hurt your towel unless you really do something to mess it up.
See a discussion here.