According this question I able to add selected item to another select.
Consider we have two select2, with same options. When I select item from box1, same item should removed from box2 and user couldn't select it. I provide it on jsfiddle.net.
Now I want to unselected it, the box2 should have that item again.
<select multiple id="Box1" name="Box1" style='width:325px;float:left;border:1px solid #80C7E2;'>
<option value="1">A</option>
<option value="2">B</option>
<option value="3">C</option>
<option value="D">D</option>
</select>
<select multiple id="Box2" name="Box2" style='width:325px;float:left;border:1px solid #80C7E2;'>
<option value="1">A</option>
<option value="2">B</option>
<option value="3">C</option>
<option value="D">D</option>
</select>
ā
$("#Box1").select2();
$("#Box2").select2();
$("#Box1").on("change", function() {
$.each($('#Box1').select2('data'), function(i, item) {
$('#Box2 option[value="'+item.id+'"]').remove();
});
});