This is the complement function to $(...).data(name, value). The name of the data store property to remove. Set a data store for 2 names then remove one of them.

$("span:eq(0)").text("" + $("div").data("test1"));
$("div").data("test1", "VALUE-1");
$("div").data("test2", "VALUE-2");
$("span:eq(1)").text("" + $("div").data("test1"));
$("div").removeData("test1");
$("span:eq(2)").text("" + $("div").data("test1"));
$("span:eq(3)").text("" + $("div").data("test2"));