Another option using linq is
[TestMethod]
public void Test()
{
var input = "it's worth a lot of money, if you can find a buyer.";
var expected = "its worth a lot of money if you can find a buyer";
var removeList = new string[] { ".", ",", "'" };
var result = input;
removeList.ToList().ForEach(o => result = result.Replace(o, string.Empty));
Assert.AreEqual(expected, result);
}