Outside of a gentle tooth brushing with warm soapy water, really no way to "clean" a corroded coin.
Lets say it was a valuable coin and you aggressively try to clean it, you would actually make it less valuable with your attempt than if you just left it alone. Collectors can spot a "whizzed" coin from a mile away, and stay away from them like the plague.
Some people use electrolysis/ultrasonic methods for cleaning, and thats generally better than hacking away at it with a wire brush, but its still going to be obvious it was messed with, and still be shunned by anyone who might have been interested in it as a legit ground find.
You could try the "tater treatment", simply stick it in a potato for a few days then remove it and wipe it down, some of the gunk may be removed. Don't try it with nickels, will turn them a pumpkin orange. With coins that are hopelessly gunked I soak them in olive oil for months, this sometimes removes enough gunk so you can at least identify the type or perhaps read a date. I have some that have been soaking for months as we speak, some day I'll take them out and wipe them down and see if they improved.
