Remove last character from a string if it contains last character as "," or ";" - C#

Input : str = "AML,Bladder Cancer,";

 
        public static string RemoveLastCharacter(string str) //str = "AML,Bladder Cancer,"
        {
            if (string.IsNullOrEmpty(str)) return "";
            if (str.EndsWith(","))
            {
                str = str.Substring(0, str.Length - 1);
            }
            else if (str.EndsWith(";"))
            {
                str = str.Substring(0, str.Length - 1);
            }
            return str;                       //  "AML,Bladder Cancer"
        }

Result : "AML,Bladder Cancer"