You can remove class active from all .tab and use $(this) to target current clicked .tab:
$(document).ready(function() {
$(".tab").click(function () {
$(".tab").removeClass("active");
$(this).addClass("active");
});
});
Your code won't work because after removing class active from all .tab, you also add class active to all .tab again. So you need to use $(this) instead of $('.tab') to add the class active only to the clicked .tab anchor