// How to replace a char in string with an Empty character
string num = "1234-1234-1234-1234";
num = num.Replace("-", " ");
// result: 1234 1234 1234 1234
// How to remove a char in string
string num = "1234-1234-1234-1234";
num = num.Replace("-", string.Empty);
// result: 1234123412341234