Editing a string using regex jquery

Question

how can i check a string if it contains a val e.g a letter, and if it does i delete it from the string? my main issue is sending the value

$('.RemoveColumnNormalCol').live("click", function () {
            var st = $(this).attr('columnLetter'); //this can be any letter 
            $('.TotalHeading').each(function () {
                var test = $(this).val();
                var replace = test.replace(/"+ st +"/g, '');
                $(this).val(replace);
            });
 });